200-301 · domain
Network Services and Security
This domain covers Cisco IOS network services and security features: DHCP, DHCP snooping, NAT/PAT, NTP, DNS, syslog, SNMP, and ACLs. Questions use drag-and-drop ordering, exhibit-based troubleshooting, and multiple-select on IPv4 versus IPv6 ACL behavior, so you must know both configuration syntax and how each feature filters or translates traffic.
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What to know about Network Services and Security
You must configure and verify DHCP relay, DHCP snooping, NAT, and ACLs on Cisco IOS, and read exhibits to isolate the broken service. The single most important thing: match each feature to the correct interface and direction, because misplaced ip helper-address, NAT inside/outside, or ACL application causes the exact failures shown.
Ordering DHCP relay and DHCP snooping steps on a Cisco switch with a remote DHCP server
Diagnosing dynamic NAT failure where inside hosts reach outside but return replies never arrive
Comparing IPv4 and IPv6 ACL statements, implicit denies, and wildcard versus prefix matching
Why learners struggle
Why Network Services and Security questions are commonly missed
Network services questions are commonly missed because candidates confuse protocol roles and port numbers. The overlap between DNS, DHCP, and NAT functions creates specific mix-ups.
Watch out for
Common Network Services and Security exam traps
- ▸Configuring ip helper-address on the wrong interface or forgetting it entirely, so DHCP broadcasts never reach the remote server.
- ▸Mixing up NAT inside and outside interface designations, which breaks return traffic even when outbound translation works.
- ▸Assuming IPv4 wildcard masks work like IPv6 prefix lengths, or forgetting that every ACL ends with an implicit deny.
Question index
All Network Services and Security questions (374)
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You are connected to R1 via the console. An extended ACL named BLOCK_SMTP has been applied inbound on interface GigabitEthernet0/1, but users on the 192.168.10.0/24 network cannot send email to the SMTP server at 203.0.113.10. Additionally, the ACL is blocking all other traffic that should be permitted. Examine the running configuration and fix the ACL so that SMTP traffic (TCP port 25) from the 192.168.10.0/24 network to the SMTP server is permitted, and all other IP traffic is allowed.
Hard2A router is configured as a DHCP server for VLAN 20. Clients on the VLAN can reach the default gateway, but they do not receive leases. Which two configuration issues on the router would directly prevent successful address assignment?
Medium3A switchport is configured with sticky MAC learning and a maximum secure MAC value of 2. What is the main benefit of sticky learning in this situation?
Hard4A switchport is configured for 802.1X authentication. What is the usual role of the RADIUS server in that design?
Hard5You are connected to R1. The network has two routers (R1, R2) and a switch (SW1) in between. R1's G0/0 connects to SW1 (192.168.1.1/24), SW1 connects to R2's G0/0 (192.168.1.2/24). R2 has a loopback (Lo0: 203.0.113.1/32) used as a management address. Configure an extended ACL on R1 so that only SSH (TCP/22) traffic from the 10.0.0.0/24 network is permitted to reach R2's loopback; all other traffic to that loopback must be denied. Then apply the ACL in the correct direction on the correct interface.
Hard6Port security is enabled with a maximum of 2 MAC addresses, but a third device connected through a small hub causes a violation. Which result is expected in restrict mode?
Medium7Refer to the exhibit. A network administrator configures NAT overload on R1 to allow internal hosts in the 10.1.1.0/24 subnet to access the Internet. After the configuration, the administrator runs the show ip nat translations verbose command and notices that several internal sessions all appear to use the same inside global port 1024. The administrator is concerned that port conflicts will occur. Based on the output, which statement is correct?
Hard8Based on the exhibit, why does the ACL still allow HTTPS traffic from the branch subnet to the server?
Hard9Which two statements accurately describe ACL behavior on Cisco devices?
Medium10Drag and drop the following steps into the correct order to implement DHCP services for clients in VLAN 10 using a centralized DHCP server in VLAN 20 and to protect the network with DHCP snooping.
Medium11Which two statements accurately describe Syslog in a Cisco network environment?
Medium12Which OSPF neighbor state indicates that the routers have already exchanged full link-state databases?
Easy13A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?
Hard14Two switches are connected by an 802.1Q trunk. CDP reports a native VLAN mismatch. Which issue is most likely to appear because of this?
Medium15Drag and drop the following steps into the correct order to configure a Cisco IOS-XE router as a DHCP server for a client VLAN and then enable a DHCP relay agent on a different interface to forward client requests to a remote server.
Hard16A network administrator has configured dynamic NAT on a Cisco router to allow internal hosts to access the Internet. Internal hosts can ping external servers, but external hosts cannot initiate connections to any internal host. The administrator checks the NAT translations. What is the most likely cause of this behavior?
Hard17A security policy requires that only one management subnet be able to initiate SSH to a router. Which approach most directly supports that requirement?
Hard18A host receives its IP address automatically but cannot resolve hostnames. Which additional service information is most likely missing from its configuration?
Medium19A junior administrator is configuring a Cisco switch port that connects to a conference room wall jack. The requirement is that only the first device that connects may use the port, and if any other MAC address is seen, the port should immediately go into an error-disabled state and require manual recovery. Which port security configuration should be applied?
Easy20Which THREE statements correctly describe the configuration and verification of NAT, PAT, and static NAT?
Medium21Exhibit: A collector is receiving traffic metadata from a router, including source IP, destination IP, protocol, and byte counts. Which feature is being used?
Medium22A switch has DHCP snooping enabled, but users still experience IP-to-MAC spoofing attacks. Which additional feature should be considered to help address that specific problem?
Hard23A switch port is configured with port security using these commands: switchport port-security switchport port-security maximum 1 switchport port-security violation restrict switchport port-security mac-address sticky A user unplugs a company laptop and connects a different unauthorized device. The interface stays up/up, but the new device has no connectivity. Which statement best explains what happened?
Hard24A host can reach remote websites by IP address but fails when using their hostnames. Which missing configuration item is the strongest suspect?
Medium25A client PC is receiving an APIPA address (169.254.x.x) instead of a valid IP from the DHCP server. The DHCP server is on the same subnet as the client. The technician runs the command 'show ip dhcp binding' and confirms that the correct scope is configured. The command 'show ip dhcp pool' shows that there are plenty of addresses remaining in the pool. The client's NIC status shows 'connected'. What should the technician do next?
Hard26Match each REST API method to the action it most closely represents in a typical network automation workflow.
Medium27Drag and drop the following steps into the correct order to configure AAA with a RADIUS server and enable 802.1X port authentication on an IOS-XE switch.
Medium28An administrator wants to allow HTTPS traffic from a source subnet to a server but deny all Telnet traffic from that same subnet to the same server. Which ACL capability is required to express that policy accurately?
Hard29Users in 10.20.30.0/24 should be allowed to browse the web but should not be able to open Telnet sessions to any remote device. Which access list entry best meets the requirement?
Medium30Refer to the exhibit. A network administrator is reviewing the NAT translations on router R1 and notices that the internal host 192.168.1.10 appears in both a static NAT entry (for ports 80 and 443) using global address 203.0.113.10, and a dynamic PAT entry (port 49152) using global address 203.0.113.1. The administrator is concerned this might indicate a misconfiguration. Based on the output, which statement is correct?
Hard31Drag and drop the following steps into the correct order to plan, configure, and apply an extended ACL that permits only HTTP traffic from the 192.168.1.0/24 network to the server 10.0.0.10, applied inbound on interface GigabitEthernet0/1.
Medium32Which four of the following are best practices for securing network services and devices? (Choose four.)
Medium33Why is an extended ACL usually placed close to the source of the traffic being filtered?
Hard34What is a key difference between SNMPv3 and earlier SNMP versions?
Medium35In AAA, what does the second A stand for?
Medium36You are connected to R1. Configure PAT (NAT overload) so that hosts on the 192.168.1.0/24 inside network can reach the Internet through the outside interface GigabitEthernet0/1 using the IP address 203.0.113.1. Additionally, configure static NAT to map internal server 192.168.1.10 to public IP 203.0.113.5. The current configuration has several errors. Identify and correct them.
Hard37You are connected to R1, a router that serves as the DNS resolver for the local network 192.168.10.0/24. Users report that they cannot resolve the hostname 'webserver.internal' to its IP address (192.168.10.50), and reverse DNS lookups for that IP return a different name. Additionally, some queries to an external domain 'example.com' time out. Diagnose and fix the DNS configuration on R1 using nslookup and dig commands where applicable, ensuring proper forward and reverse resolution for internal hosts and reachability to external DNS servers.
Hard38A switch port is configured with port-security violation mode restrict. Which two statements are true when an unauthorized MAC address appears?
Medium39You are connected to R1 via console. R1 is a router that needs to provide DHCP services to hosts on VLAN 10 (192.168.10.0/24) and VLAN 20 (192.168.20.0/24). The router has two subinterfaces on GigabitEthernet0/0: G0/0.10 (192.168.10.1/24) and G0/0.20 (192.168.20.1/24) with 802.1Q encapsulation. Configure R1 as a DHCP server for both VLANs, excluding addresses 192.168.10.1-10 and 192.168.20.1-10, with a lease of 1 day. Ensure DNS server 8.8.8.8 is provided.
Medium40A client on VLAN 20 must obtain an IPv4 lease from a DHCP server located on VLAN 100. Which feature is required on the Layer 3 interface for VLAN 20?
Medium41PCs in VLAN 40 are not receiving addresses from the centralized DHCP server at 172.16.1.10. What should be configured on the VLAN 40 default gateway interface?
Hard42Which ACL type can filter using source and destination IP addresses as well as TCP or UDP port numbers?
Medium43You are connected to R1. The network uses 192.168.1.0/24 for internal hosts and 203.0.113.0/29 for the public IP pool (203.0.113.2 is the outside interface). Configure PAT so that inside hosts can reach the Internet using the pool address 203.0.113.2. Also configure static NAT to map internal server 192.168.1.10 to 203.0.113.3. The initial config has errors; identify and fix them.
Hard44A router is configured for NAT overload, but translations never appear when inside users browse the internet. Which issue is most likely?
Medium45A switch has DHCP snooping enabled and Dynamic ARP Inspection enabled on VLAN 30. A printer with a static IP on VLAN 30 cannot communicate because its ARP packets are being dropped. What is the best fix?
Hard46Refer to the exhibit. An administrator has configured NAT on router R1 to allow hosts on the 192.168.1.0/24 LAN to access the Internet. However, users report that they cannot reach external websites. The administrator runs the show ip nat translations command. What is the most likely reason for the problem?
Hard47A small office uses a Cisco router as its DHCP server for the 192.168.50.0/24 LAN. The administrator wants client devices to resolve internal hostnames such as printer.office.local without contacting an external resolver first. Which DHCP option should be configured on the router to supply the internal DNS server address to clients?
Easy48Which three of the following are characteristics of DHCP snooping? (Choose three.)
Medium49A network administrator configured dynamic NAT on a Cisco router to allow internal hosts to access the internet. After the configuration, users report that they can access some websites but not others. The administrator checks the router and discovers that the NAT translation table is full, and new connection attempts are being dropped. What is the most likely cause of this issue?
Hard50You are connected to R1 via the console. R1 connects two networks: GigabitEthernet0/0 (192.168.1.1/24) and GigabitEthernet0/1 (192.168.2.1/24). Create an extended ACL named BLOCK_HTTP that denies HTTP traffic (tcp port 80) from the 192.168.1.0/24 network to the 192.168.2.0/24 network, but permits all other IP traffic. Apply this ACL inbound on GigabitEthernet0/0.
Medium51R1 has the following routes installed: O 10.10.10.0/24 via 192.0.2.2 S 10.10.10.128/25 via 198.51.100.2 S* 0.0.0.0/0 via 203.0.113.1 A packet destined for 10.10.10.200 arrives at R1. Which route is used?
Hard52A security team wants device administrators to log in with individual named accounts instead of sharing one generic admin account. Which security objective does that most directly improve?
Hard53An administrator wants an access-layer interface to shut down immediately if another switch is connected accidentally. Which feature best meets that requirement?
Medium54A user types www.example.com into a browser. Which service is used first to resolve that name into an IP address?
Easy55After securing a switch by running 'ip ssh version 2' and generating RSA keys with 'crypto key generate rsa modulus 1024', remote SSH connections fail with a 'key exchange error'. A check of the SSH client’s documentation reveals it requires a minimum 2048-bit RSA key for SSH version 2. What should the technician do next?
Hard56A router allows SSH management from anywhere on the internal network. A new policy requires that only the management subnet 10.50.50.0/24 be allowed to initiate SSH to the device. Which approach best enforces that requirement?
Hard57Match each security concept to its most accurate meaning.
Medium58A branch router has only one WAN link connected to an Ethernet handoff from the provider. Which static default route is generally the better choice?
Medium59A named standard ACL is configured to permit only the 192.168.30.0/24 subnet, but users from 192.168.31.0/24 are still passing traffic. What is the most likely reason?
Hard60A company wants to reduce the chance that unused switch ports can be exploited. Which action best aligns with that goal?
Hard61Which wireless security method is considered strongest among these choices for modern enterprise WLAN deployments?
Medium62You are connected to R1. The network currently permits all HTTP traffic from hosts on the 192.168.1.0/24 LAN to reach the web server at 203.0.113.10, but SSH traffic (TCP port 22) from the same LAN is being blocked. Additionally, you must ensure that no other traffic from the LAN reaches the server. Configure an extended ACL on R1 to allow only HTTP and SSH from the LAN to the server, and apply it inbound on the correct interface. Verify your solution.
Hard63A host reaches websites by IP address but fails when using hostnames. Which service is the strongest suspect?
Hard64Match each network service to its primary function.
Easy65An engineer configures NAT overload on a router for inside users. Which resource is primarily used to let many internal hosts share one public IPv4 address?
Medium66A router is configured with an access list intended to block Telnet from 192.168.10.0/24 to 10.1.1.10, but Telnet still works. What is the most likely reason?
Medium67A host sends a packet larger than the outgoing interface MTU, and the IPv4 header has the Don't Fragment bit set. What will a router do with the packet?
Hard68Match each DHCPv4 message in the DORA process to its role.
Easy69A network administrator has configured a DHCP server on VLAN 100 with an IP address of 192.168.100.10/24. Clients on VLAN 200 (192.168.200.0/24) report that they cannot obtain an IP address via DHCP. The router is configured with a DHCP relay on the VLAN 200 interface. The administrator checks the router configuration and verifies that the relay is in place, but clients still fail to get an address. The switch that the router and clients connect to has DHCP snooping enabled. What is the most likely cause of this issue?
Hard70A network administrator is configuring a site-to-site IPsec VPN between two Cisco routers. The administrator wants to ensure that the VPN traffic is protected by both encryption and integrity checking. Which combination of IPsec protocols should be used?
Medium71A company wants all routers and switches to use a common time source so log timestamps line up during incident review. Which two statements about NTP are correct?
Easy72A router is configured for PAT overload. What does the inside global address represent for an internal PC?
Medium73An administrator wants to permit SSH management access but block Telnet access to a device. Which statement best reflects that design goal?
Hard74Drag and drop the following steps into the correct order to configure NTP with authentication on a Cisco router.
Medium75You are connected to R1 via the console. R1 is a router that needs to provide DHCP services for hosts on VLAN 10 (192.168.10.0/24) and VLAN 20 (192.168.20.0/24). The DHCP server is located on VLAN 10 at 192.168.10.100, but hosts on VLAN 20 cannot reach it directly. Configure R1 to forward DHCP broadcasts from VLAN 20 to the DHCP server.
Medium76Users receive addresses from the correct subnet and can reach destinations by IP address, but they cannot browse by hostname.
Medium77An engineer successfully authenticates to a controller and receives a token. What is the usual reason for including that token in later API requests?
Medium78Drag and drop the following steps into the correct order to plan, configure, and apply an extended ACL that blocks Telnet traffic from the 192.168.1.0/24 network to the 10.0.0.0/24 network, applied inbound on the interface facing the source.
Medium79Which TWO statements correctly describe the behavior of standard ACLs and their placement on interfaces?
Medium80A network technician has configured static NAT with the command ip nat inside source static 192.168.1.10 203.0.113.10. The web server at 192.168.1.10 is accessible from the internet on TCP port 80 but not on TCP port 443. The ACL applied to the outside interface permits all IP traffic. What is the most appropriate next step to troubleshoot this issue?
Hard81You are connected to R1. The internal network 192.168.1.0/24 must be able to access the Internet via PAT (NAT overload) using the outside interface G0/1 with IP 203.0.113.1. Additionally, a web server at 192.168.1.100 must be reachable from the Internet via static NAT to the same outside interface. The current configuration has errors. Correct the NAT configuration so that inside hosts can browse the web and the server is reachable from outside.
Hard82Which TWO statements are true regarding the configuration and placement of standard and extended ACLs on a router?
Medium83Users complain that log timestamps from several routers do not line up with one another. Which two actions are most appropriate?
Medium84Which traffic type is typically most sensitive to delay and jitter and is commonly prioritized with QoS?
Medium85A company wants wireless guest users to authenticate with a username and password stored on a central server, without deploying client certificates. The wireless LAN controller must forward authentication requests to the server. Which protocol should be used between the WLC and the authentication server?
Easy86Drag and drop the following steps into the correct order to configure AAA with a RADIUS server and 802.1X port authentication on an IOS-XE switch.
Hard87An ACL is intended to block Telnet from 10.1.1.0/24 to router VTY access while still allowing SSH from the same subnet. Which statement best explains why an extended ACL is appropriate here?
Hard88Match each security concept to its most accurate purpose.
Medium89You are connected to R1. Configure PAT (NAT overload) so that hosts on the 192.168.1.0/24 LAN can access the Internet via the outside interface GigabitEthernet 0/1 with IP 203.0.113.2/29. The current configuration has an incorrect inside/outside interface assignment and a missing overload keyword. Fix all issues.
Hard90Which two statements accurately describe why least privilege and source restriction work well together for administrative access?
Medium91Why might voice traffic be placed in a priority queue on a WAN link?
Medium92Which TWO actions does DHCP snooping perform by default on a Cisco switch?
Medium93You are troubleshooting PAT and static NAT on R1. The inside network 192.168.10.0/24 must be translated to the public IP 203.0.113.1 (interface G0/1) using port address translation. Additionally, the server at 192.168.10.100 must be reachable from the outside via static NAT to 203.0.113.5. The current configuration is not working. Identify and correct the errors in the running config on R1.
Hard94Which two statements accurately describe DNS in everyday network use?
Medium95Refer to the exhibit. A network engineer is troubleshooting a DHCP issue where DHCP clients on the LAN subnet are sending DHCPDISCOVER messages but the DHCP server does not receive them. The output of the show ip dhcp binding command on R1 is shown. What is the most likely cause of the problem?
Hard96A network administrator is troubleshooting a switch that is receiving DHCPDISCOVER messages from a client on VLAN 20, but the DHCP server on a different subnet never sees those requests. The interface VLAN 20 has the address 10.20.0.1/24, and the DHCP server address is 10.99.0.10. Which command should be applied to enable the switch to forward these requests to the server?
Medium97A junior administrator is configuring a Cisco router that must forward DHCP requests from the 10.20.30.0/24 LAN to a DHCP server at 192.168.100.50. The LAN interface is Gi0/0 with IP 10.20.30.1. Which single command is required on Gi0/0 so the router relays these broadcasts?
Medium98Which two statements accurately describe why logs and accounting records both matter in secure operations?
Medium99Which feature helps prevent a rogue DHCP server from handing out addresses on a campus switch network?
Medium100Refer to the exhibit. A network administrator is troubleshooting connectivity issues. Hosts on the 192.168.10.0/24 network cannot reach servers on the 192.168.20.0/24 network, but they can successfully reach other networks, including the Internet. The administrator runs the show ip access-lists command on the router (output shown). What is the most likely cause?
Hard101Drag and drop the following steps into the correct order to configure AAA with a RADIUS server and 802.1X port authentication on a Cisco IOS-XE switch.
Medium102Which TWO statements accurately describe Network Address Translation (NAT) types?
Medium103Why is disabling unused services on network devices considered a sound security practice?
Medium104Which two statements accurately describe why SSH is preferred over Telnet for device administration?
Medium105You are connected to R1. Configure static NAT for a public web server (198.51.100.10 to 192.168.1.10) and PAT for the 192.168.1.0/24 LAN to use interface GigabitEthernet0/1 with overload. The current configuration has misconfigured NAT that prevents both types from working. Identify and fix the issues so that internal hosts can access the internet and external hosts can reach the internal web server.
Hard106Exhibit: A user can ping 8.8.8.8 successfully but cannot browse to www.example.com by name. Which service is the most likely failing component?
Medium107You are connected to R1 via console. R1's GigabitEthernet0/0 (10.0.0.1/30) connects to an ISP, and GigabitEthernet0/1 (192.168.1.1/24) connects to the internal LAN. The network administrator needs to monitor R1's system messages. Configure R1 to send syslog messages with severity level 5 (notifications) and above to the syslog server at 10.0.0.2. Also, ensure that logging is enabled and that messages include the timestamp and source interface.
Medium108A switch interface connected to a Cisco IP phone with a PC behind it must carry voice and data correctly. Which two switchport commands are appropriate on that access port?
Hard109You are connected to R1. The network administrator wants to permit only HTTPS traffic (TCP port 443) from the 192.0.2.0/24 network to the 203.0.113.0/24 network, while denying all other IP traffic. Currently, an ACL applied inbound on G0/1 is blocking all traffic, including HTTPS. Identify the issue and correct the ACL configuration so that only HTTPS traffic is permitted.
Hard110Why is NTP especially valuable when a network uses centralized Syslog servers?
Medium111A network administrator is configuring DHCP snooping on a Cisco Catalyst switch. The switch has a trunk port Gi1/0/24 connecting to another switch, and several access ports connecting to end-user PCs. The administrator issues the commands 'ip dhcp snooping', 'ip dhcp snooping vlan 10', and then configures interface Gi1/0/24 with 'ip dhcp snooping trust'. A PC connected to Gi1/0/5 (an untrusted port) sends a DHCPDISCOVER. What will the switch do with this DHCPDISCOVER message?
Medium112A switch is configured with DHCP snooping and Dynamic ARP Inspection. Hosts suddenly lose connectivity after changing IP settings manually. Which explanation is strongest?
Hard113Drag and drop the following steps into the correct order to configure PAT (overload) on a Cisco router using a single public IP address on the outside interface.
Medium114A branch router uses PAT for Internet access. Users can browse out, but the administrator wants a specific internal web server to be reachable from outside on a consistent public address. Which design fits that requirement best?
Hard115Exhibit: A company wants to export traffic statistics from routers to a collector for visibility into top talkers and application usage. Which two statements are accurate?
Hard116You are connected to R1 via the console. R1 is an NTP client that should synchronize its clock with NTP server 192.168.1.100. The timezone is UTC-5 (Eastern Standard Time). Configure NTP on R1 so that it becomes an NTP client. Additionally, configure the router to log NTP synchronization status messages to the console and buffer logging using the numeric severity level 6 (informational).
Medium117An automation script needs to send a bearer token when calling a controller REST API over HTTPS. Where is that token most commonly included?
Medium118You are connected to R1, a Cisco IOS-XE router that serves as the DNS resolver for the local network. The router can reach the DNS server at 198.51.100.53, but internal hosts cannot resolve the hostname 'fileserver.courseiva.com' (expected IP 203.0.113.10). Which configuration will resolve the issue?
Hard119A network administrator has configured 802.1X port-based authentication on a Cisco IOS-XE switch for a new access port connected to a user workstation. The workstation is failing to gain network access. The switch port is in the 'authorized' state, but the workstation cannot ping the default gateway. The administrator checks the running configuration and the authentication session details. What is the most likely cause of the issue?
Hard120An engineer is allowed to log in to a router but cannot enter configuration mode. Which AAA function most directly explains that outcome?
Hard121Drag and drop the following IOS-XE CLI commands into the correct order to configure AAA with a RADIUS server and then enable 802.1X port authentication on an interface.
Medium122A network engineer has enabled DHCP snooping on a Catalyst switch to prevent rogue DHCP servers. All access ports in VLAN 10 are untrusted. A router attached to a trunk port on the switch acts as the default gateway for VLAN 10 and is configured with the ip helper-address 10.1.2.5, which points to a remote DHCP server. After enabling DHCP snooping, hosts in VLAN 10 cannot obtain IP addresses; packet captures show DHCPDISCOVER messages are sent, but no DHCPOFFER is received. What is the most likely cause?
Hard123A user reports that their desk port stopped working immediately after they connected a small switch. The interface shows err-disabled, and the log mentions BPDU Guard. What most likely happened?
Medium124Which protocol is most directly responsible for keeping device clocks synchronized across a network?
Medium125Which TWO statements correctly describe the behavior of PAT (Port Address Translation) as configured on a Cisco router?
Medium126You are connected to R1, a branch router. Configure an extended ACL named BRANCH_IN that permits only HTTP (TCP port 80) traffic from the internal network 192.168.1.0/24 to the web server at 203.0.113.10, and permits ICMP echo-reply from any source to any destination. Apply the ACL inbound on the interface facing the internal network. Then verify that only the specified traffic is allowed.
Hard127A network technician is troubleshooting a DHCP relay issue. The router at the branch office is supposed to forward DHCP requests from local clients to a central DHCP server. Clients connected to Gi0/1 are not receiving IP addresses. The technician verifies that the DHCP server is reachable from the router, that no ACLs are blocking DHCP traffic, and that the DHCP scope on the server has available leases. Upon checking the running configuration, the technician notices that the ip helper-address command is applied to interface Gi0/0 (the WAN link toward the server) instead of Gi0/1. What should the technician do next?
Hard128A network engineer has implemented DHCP snooping on a Cisco switch to prevent unauthorized DHCP servers. The switch's VLAN 100 SVI is configured with ip helper-address to relay DHCP requests to a legitimate server in VLAN 200. Clients in VLAN 100 cannot obtain IP leases, even though the DHCP server is reachable from the switch and has available addresses.
Hard129A switch stack is running PVST+. Users on VLAN 40 lose connectivity for roughly 30 seconds every time the uplink on SW2 flaps. Based on the exhibit, which change would most directly improve convergence for this VLAN?
Medium130You are connected to R1. The inside network 192.168.1.0/24 must be translated to the outside interface IP (198.51.100.1) using PAT (NAT overload). Additionally, a static NAT entry must map host 192.168.1.10 to 203.0.113.10. The current configuration is incomplete and contains errors. Correct the configuration so that both translations work properly.
Hard131Why is NTP especially valuable when a company uses a centralized Syslog server?
Medium132You are connected to R1 via console. R1 is a router that connects two internal subnets (192.168.1.0/24 and 192.168.2.0/24) to the internet via a serial link to ISP. Currently, no ACL is applied. Your task is to configure an extended named ACL on R1 that permits only HTTP (TCP/80) and HTTPS (TCP/443) traffic from the 192.168.1.0/24 subnet to the internet, and denies all other traffic from that subnet. Traffic from 192.168.2.0/24 must be permitted without restriction. Apply the ACL inbound on the interface facing the internal subnets. Additionally, verify that the implicit deny is not blocking necessary traffic by ensuring that the ACL correctly handles the traffic.
Hard133A network engineer successfully logs in to a router, but cannot enter configuration mode because the command is rejected by policy. Which AAA function is controlling this behavior?
Medium134Inside hosts can reach the internet only one at a time. What is the most likely NAT issue?
Hard135Two static routes exist for the 203.0.113.0/24 network: one pointing to ISP-A with an administrative distance of 10, and another pointing to ISP-B with an administrative distance of 5. Packets for that subnet are leaving through ISP-B. What explains this behavior?
Hard136Match each access-control term to its most accurate meaning.
Medium137Drag and drop the following steps into the correct order to configure a Cisco IOS-XE router as a DHCP server for a local subnet and enable a DHCP relay agent on a different interface to forward client requests to that server.
Hard138Which two statements correctly describe syslog severity levels?
Easy139Refer to the exhibit. A network administrator notices that newly connected devices on the 192.168.1.0/24 subnet are failing to obtain IP addresses via DHCP and are instead assigning themselves APIPA addresses. The administrator issues the show ip dhcp pool command on the router and receives the output shown. What is the most likely cause of this issue?
Hard140A router is configured as follows: interface g0/1 ip address 172.16.1.1 255.255.255.0 ip helper-address 10.20.20.10 Hosts on 172.16.1.0/24 are not receiving addresses from the DHCP server at 10.20.20.10. The server is reachable by ping from the router. What is the purpose of the ip helper-address command in this scenario?
Medium141Refer to the exhibit. A network engineer is troubleshooting an issue where syslog messages at severity 6 (informational) and severity 7 (debugging) are not being sent to the syslog server at 192.168.100.50, even though the device appears to generate these messages locally. Based on the exhibit, what is the most likely cause?
Hard142Match each security control or idea to its most accurate purpose.
Medium143Exhibit: An administrator wants inside hosts in 192.168.10.0/24 to reach the internet using one public IP address on the edge router. Which feature is being used?
Medium144Which of the following sequences correctly orders the steps to plan, configure, and apply an extended ACL that permits HTTP traffic from the 192.168.1.0/24 subnet to the server at 10.0.0.1, and deny all other IP traffic, applied inbound on interface GigabitEthernet0/1?
Medium145Which DHCP message does the client send to formally accept an offered address?
Medium146You are connected to R1. Configure DHCP services so that hosts on VLAN 10 (192.168.10.0/24) can obtain IP addresses from R1. Additionally, configure the switch SW1 to prevent rogue DHCP server attacks on that VLAN. The current configuration has a misconfigured helper-address and an excluded-address range that is too broad.
Hard147A network engineer notices that hosts in the 192.168.2.0/24 network connected to router R1's GigabitEthernet0/1 interface cannot reach the Internet. R1 has a standard ACL 10 configured as 'access-list 10 permit 192.168.1.0 0.0.0.255' and applied inbound on interface GigabitEthernet0/0, which connects to the 192.168.1.0/24 LAN. What is the most likely cause?
Hard148A network administrator needs to configure a Cisco router to act as a DHCP server for a small LAN. The router should lease addresses from the 192.168.10.0/24 network, exclude addresses 192.168.10.1 through 192.168.10.10 for static devices, and set the default gateway to 192.168.10.1. Which command is required to exclude the static addresses from the DHCP pool?
Medium149Which switch security feature uses DHCP snooping bindings to validate ARP packets and help stop ARP spoofing?
Hard150Match each operations or assurance technology to its most accurate purpose.
Medium151A network engineer notices that an NMS at 10.1.1.200 cannot poll a router that has SNMPv2c configured with community string 'public'. What is causing this issue?
Hard152A network team wants centralized logging and also wants log timestamps from different devices to line up accurately. Which combination best supports that goal?
Medium153You are connected to R1, a Cisco IOS-XE router acting as the network's DNS client. The network uses a local DNS server at 203.0.113.10 for internal name resolution. Users report that the hostname 'fileserver.courseiva.local' cannot be resolved, while other names work fine. Diagnose and fix the DNS resolution failure so that 'fileserver.courseiva.local' resolves correctly.
Hard154An ACL entry reads: access-list 25 permit 192.168.8.0 0.0.0.15 Which address range does this statement match?
Medium155Why is centralized logging especially useful when combined with NTP?
Medium156Which three of the following are characteristics of DHCP snooping on a Cisco switch? (Choose three.)
Medium157You are connected to R1. The network has two routers: R1 (192.168.1.0/24 LAN) and R2 (Internet gateway). R1's inside LAN (192.168.1.0/24) must be translated to the public IP 203.0.113.1 using PAT (NAT overload) for Internet access. Additionally, the server at 192.168.1.100 must be reachable from the Internet via static NAT to 203.0.113.5. The current configuration is broken. Identify and fix the issues so that both PAT and static NAT work correctly.
Hard158Which TWO DNS record types are most commonly used together to verify both forward and reverse DNS mappings for an IPv6 address?
Medium159Drag and drop the following steps into the correct order to sequence the DNS resolution process from a client query to receiving an A-record response, followed by the diagnostic workflow using nslookup and dig to identify a missing or incorrect A-record.
Medium160A router is performing PAT for inside users. Which detail allows multiple inside sessions to share one public IPv4 address at the same time?
Hard161You are connected to the multilayer switch MLS1 in a branch network. The DHCP server on router R1 is supposed to serve the 192.168.20.0/24 VLAN 20, but clients in VLAN 20 are not receiving IP addresses. Additionally, a rogue DHCP server has been detected on VLAN 20. Configure MLS1 to enable DHCP snooping on VLAN 20, set the trust state on the uplink port to R1, and limit the rate of DHCP packets on access ports. Then, on R1, correct the DHCP configuration so that the pool for VLAN 20 uses the correct default-router (192.168.20.1) and DNS server (8.8.8.8), and ensure that the excluded-address range is not too large (exclude only the first 10 addresses). Verify the solution.
Hard162An ACL permits only tcp 10.10.10.0/24 host 192.0.2.10 eq 443 and has no other permit entries. What happens to an ICMP echo request from 10.10.10.5 to 192.0.2.10?
Hard163Which three of the following statements about Network Address Translation (NAT) are correct? (Choose three.)
Medium164A network administrator is configuring a site-to-site IPsec VPN between two Cisco routers. The administrator wants to ensure that the encryption and integrity of the data traffic are provided separately, using ESP. Which statement correctly describes how ESP provides these services?
Hard165Why is NTP especially useful when devices send logs to a centralized Syslog server?
Medium166Which two actions are reasonable examples of basic device-hardening practice?
Medium167Which service would a client most directly rely on to convert `server.example.com` into an IP address?
Medium168A controller-based WLAN uses 5 GHz in an open office. Clients keep disconnecting when users roam between APs, but signal strength remains strong. Based on the exhibit, what is the most likely problem?
Hard169An administrator wants to block all Telnet access to a router’s VTY lines and allow only SSH. Which change most directly supports that goal?
Hard170Match each service to the kind of problem it most directly helps solve.
Medium171A device administrator can log in securely over SSH, but the organization still insists on restricting source IP ranges and keeping detailed logs. Which statement best explains that decision?
Hard172Which two statements accurately describe DNS and DHCP?
Medium173Based on the exhibit, which configuration should be added to restore DHCP service for clients in VLAN 30?
Hard174Which two statements accurately describe the value of named administrative accounts?
Medium175You are configuring a Cisco switch port in a lobby area where only one device should ever connect. You want the port to learn the first MAC address it sees, and if a different MAC address appears later, you want the port to drop frames from the new address while still allowing the original device to communicate. Which port-security violation mode meets this requirement?
Medium176Which two statements accurately describe why NetFlow is useful for operations teams?
Medium177An administrator sees high interface utilization through SNMP graphs but wants to identify which conversations are responsible. Which addition best closes that visibility gap?
Hard178Users can reach a server by IP address but not by hostname. Which service should be checked first?
Easy179Which two actions help protect access-layer switch ports from rogue DHCP servers?
Medium180A network engineer notices that clients in the 192.168.10.0/24 subnet are receiving the IP address 192.168.10.1 from the DHCP server, causing a duplicate IP conflict with the router’s own interface. What is the most likely cause?
Hard181A network administrator is troubleshooting an issue where internal hosts can ping the company's web server by IP address (192.0.2.10) but cannot access it using the fully qualified domain name www.example.com. The DNS server (192.0.2.5) is reachable and responds to queries. The administrator runs nslookup www.example.com from a host and receives the following output: C:\> nslookup www.example.com Server: UnKnown Address: 192.0.2.5 Name: www.example.com Address: 192.0.2.20 Based on the output, what is the most likely cause of the problem?
Hard182Based on the exhibit, what is the most likely reason PAT is not working correctly?
Hard183Which THREE statements correctly describe the configuration of AAA with RADIUS or TACACS+ on Cisco IOS-XE?
Medium184You are connected to R1 via the console. The network has a DNS server at 203.0.113.10 that should resolve www.example.com to 203.0.113.100. However, when you ping www.example.com, it fails. Diagnose and resolve the DNS resolution issue. The DNS server is reachable via ping, but nslookup from R1 returns a server failure. Configure R1 so that it can successfully resolve www.example.com. Additionally, verify that the DNS server is correctly configured for forward and reverse lookups.
Hard185Users in 10.10.10.0/24 must be prevented from reaching the web server at 172.16.1.10 over HTTP, but all other traffic should be allowed. Which ACL entry best matches the requirement?
Hard186Drag and drop the following steps into the correct order to trace the DNS resolution process from a client query to receiving an A-record response.
Medium187Based on the exhibit, why are clients in VLAN 70 failing to resolve hostnames even though they can reach remote IP addresses?
Hard188Match each service or visibility technology to the most appropriate use case.
Medium189An internal server must always be reachable from outside using the same public IP address. Which translation approach is most appropriate?
Hard190A host receives a correct IP address and subnet mask from DHCP but still cannot reach remote networks. Local subnet communication works. Which missing DHCP option is the strongest suspect?
Hard191A network team wants routers and switches to have consistent timestamps in logs so event correlation is accurate during an outage. Which service should they verify first?
Medium192A router is configured with a static NAT mapping for an internal server. What is the main operational advantage of this design for outside clients?
Hard193Refer to the exhibit. A network engineer is troubleshooting DHCP issues on a branch office network. Several users report that new devices are unable to obtain IP addresses, even though the DHCP pool configured on R1 appears to have sufficient free addresses. The engineer executes the show ip dhcp conflict command and observes the output. Based on the output, what is the most likely cause of the problem?
Hard194SW2 receives the following STP details for VLAN 10: The root bridge ID is 32768:0001.0001.0001 (SW1), and SW2's bridge ID is 32768:0002.0002.0002. Its interface Gi0/1 has a path cost of 4 to the root, while Gi0/2 has a path cost of 19. Based on this information, which statement is correct?
Hard195Which two statements accurately describe why NTP and Syslog are often configured together?
Medium196Exhibit: PCs in VLAN 20 are not receiving addresses from a DHCP server in another subnet. The switch SVI for VLAN 20 is up, and routing is working. Which configuration is most likely missing on the gateway for VLAN 20?
Medium197Refer to the exhibit. An administrator is trying to access a web server in the DMZ at 192.168.1.10 using HTTPS, but the connection times out. The web server is confirmed to be running and listening on both port 80 and port 443. The administrator examines the access list configuration on the perimeter router. Based on the output of the show access-lists command, what is the most likely cause of the failure?
Hard198An administrator wants to prevent users from browsing to one specific web server while still allowing them to reach other web destinations. Which ACL design principle is most important here?
Hard199An engineer wants all devices to send logs to 10.10.10.50 and also stamp those logs with consistent time from 10.10.10.60. Which two configurations are required on a Cisco device?
Hard200A user can authenticate successfully to a network device but is denied access to certain commands. Which statement best explains the situation?
Hard201A network administrator wants to receive an immediate notification from a device when a significant event occurs, rather than polling the device repeatedly. Which SNMP feature is most associated with that requirement?
Hard202Exhibit: A standard ACL meant to block host 10.10.10.50 from reaching any remote network was applied inbound on the branch router's LAN interface, but users report that all local traffic from that host is now blocked. What is the better placement?
Hard203Why is the combination of strong authentication and centralized logging better than either control by itself?
Hard204Which two statements accurately describe basic WLAN security at the CCNA level?
Medium205Users can browse websites by IP address but not by hostname. The default gateway is reachable and general internet connectivity works. Which two causes are the most likely?
Hard206Which two statements accurately describe why DNS issues can look like general connectivity problems to users?
Medium207Which three features are used to mitigate Layer 2 security threats on a Cisco switch? (Choose three.)
Medium208You are connected to R1, a multilayer switch acting as a DNS forwarder for two VLANs. Users on VLAN 10 report that they cannot resolve 'files.example.com' while VLAN 20 works fine. The DNS server 198.51.100.53 is reachable but returns SERVFAIL for queries from subnet 192.168.10.0/24, while server 203.0.113.53 responds correctly for both VLANs. Diagnose and fix the DNS resolution issue using nslookup and dig, then adjust the IOS-XE configuration to ensure proper name resolution. Choose the best fix that permanently resolves the problem.
Hard209A small office wants branch routers to automatically hand out IP addresses, default gateway values, and DNS servers to clients. Which service should be configured?
Easy210A switch port is configured with DHCP snooping trust on the uplink toward the legitimate DHCP server, and DHCP snooping is enabled on the user VLAN. A user connects a rogue DHCP server to an untrusted access port. Which two statements describe what DHCP snooping does in this situation? (Choose two.)
Hard211You are connected to R1. The inside network 192.168.1.0/24 must be able to reach the internet via PAT (overload) using the public IP 203.0.113.1 on interface GigabitEthernet0/1. Additionally, a web server at 192.168.1.10 must be reachable from the internet via static NAT to 203.0.113.10. The current configuration is not working. Identify and fix all issues.
Hard212Refer to the exhibit. A network administrator is troubleshooting an NTP synchronization issue on R1. The router is configured with the command ntp server 10.1.1.100, but the clock remains unsynchronized. The administrator issues the show ntp status command. What is the most likely cause of the problem?
Hard213Which security concept gives a user only the permissions required to perform assigned tasks and nothing more?
Medium214R1 and R2 should form an OSPF adjacency on their shared GigabitEthernet link, but they remain stuck in EXSTART. What is the most likely cause?
Hard215Which two statements about NTP are correct? (Choose two.)
Medium216Which two statements about standard and extended IPv4 ACLs are correct?
Medium217Which two statements accurately describe why source restriction and logging are often used together for administrative access?
Medium218Drag and drop the following steps into the correct order to configure a Cisco IOS-XE router as a DHCP relay agent and verify the DHCP DORA process for a client on a remote subnet. OPTIONS: A: Configure the ip helper-address command on the interface facing the client, then verify connectivity to the DHCP server, and finally capture the DORA process using debug ip dhcp relay. [CORRECT] B: Configure the ip helper-address command on the interface facing the DHCP server, then verify connectivity to the client, and finally capture the DORA process using debug ip dhcp server packet. C: Configure the ip dhcp relay information option command on the interface facing the client, then verify connectivity to the DHCP server, and finally capture the DORA process using debug ip dhcp server packet. D: Configure the ip helper-address command on the interface facing the client, then capture the DORA process using debug ip dhcp server packet, and finally verify connectivity to the DHCP server.
Hard219Which field is modified by each router hop in an IPv4 packet to prevent endless forwarding loops?
Medium220A network administrator is configuring a Cisco router to act as a DHCP server for a new VLAN. The router must provide IP addresses, default gateway, and DNS server information to clients. Which two commands are required in the DHCP pool configuration to provide the default gateway and DNS server to clients? (Choose two.)
Medium221The SVI for VLAN 20 has `ip nat outside` and the WAN interface has `ip nat inside`. Hosts in VLAN 20 must reach the internet through PAT, but users report no external connectivity. Which configuration issue best explains the problem?
Hard222Drag and drop the following steps into the correct order to sequence the DNS resolution process from a client query to receiving an A-record response, followed by the nslookup and dig diagnostic workflow for troubleshooting missing or wrong DNS records.
Medium223After hardening SSH by disabling password authentication and restricting access to an ACL permitting only the management subnet 10.1.10.0/24, configuring RADIUS AAA authentication, enabling port security with a maximum of two MAC addresses on all access ports, and implementing DHCP snooping and DAI on VLAN 10, the administrator finds that users in VLAN 10 obtain DHCP addresses and access the network normally, but SSH from the management workstation (10.1.10.20) to the switch fails with timeouts.
Hard224You are connected to R1. The network uses DNS to resolve hostnames for remote device management. Currently, R1 cannot resolve the hostname 'ServerA' via DNS. Using the nslookup and dig commands, you have gathered the following outputs: nslookup ServerA Server: 203.0.113.1 Address: 203.0.113.1#53 Name: ServerA.example.com Address: 203.0.113.10 dig ServerA ... ;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: ... ... The show running-config command shows that 'ip domain-lookup' is enabled, the name-server is 203.0.113.1, and no static host entries are configured. Diagnose and fix the DNS resolution failure. Ensure that R1 can successfully resolve 'ServerA' to its intended IP address 198.51.100.10.
Hard225Clients on a network can browse the internet by IP address but fail when using hostnames. What is the most likely problem?
Hard226On a router performing NAT, where should ip nat inside be applied?
Medium227Users in 10.10.10.0/24 must be prevented from reaching the web server at 172.16.1.10 over HTTP, but all other traffic should be allowed. Which ACL entry should appear first in the ACL?
Medium228You are connected to R1. Configure AAA with a RADIUS server at 10.0.0.2 using key 'cisco123' for authentication. Then troubleshoot why 802.1X on interface GigabitEthernet0/1 remains in unauthorized state. Ensure that the default login authentication uses RADIUS first, then local fallback, and fix any configuration issues that prevent 802.1X from working.
Hard229A host can reach other devices on its local subnet, but it cannot reach remote networks. The host has a valid IP address and subnet mask. Which missing item is the strongest suspect?
Medium230After enabling Dynamic ARP Inspection on VLAN 20, a network engineer notices that some hosts lose connectivity. The affected hosts have correct IP addresses and MAC addresses, but they cannot ping the default gateway. All other hosts on the same VLAN work fine. Further investigation reveals that the non-functioning hosts are using static IP configurations, while the working hosts are DHCP clients. What is the most likely cause?
Hard231You are connected to R1 via the console. R1 is a router that connects to the internet via GigabitEthernet0/0 (198.51.100.1/30) and to the internal network via GigabitEthernet0/1 (10.1.1.1/24). You need to implement a security policy that permits HTTP traffic (port 80) from the internal network to a web server at 10.1.1.100, and denies all other traffic from internal hosts to the internet. The ACL should be named 'INTERNET-FILTER' and applied inbound on GigabitEthernet0/1.
Medium232Drag and drop the following steps into the correct order to plan, configure, and apply an extended ACL that permits web traffic from the 10.1.1.0/24 network to the server 192.168.2.10 while blocking all other traffic inbound on GigabitEthernet0/1.
Medium233Which TWO DHCP snooping trust states are valid on a Cisco switch? (Choose two.)
Medium234Exhibit: A client can ping 8.8.8.8 but cannot browse to www.example.com. Which service is most likely failing?
Hard235Based on the exhibit, what is the strongest explanation for why clients can browse by IP address but not by hostname?
Hard236A small office network uses a single public IP address on its router's WAN interface. The network administrator needs to allow all internal hosts to access the internet, but must also ensure that an internal web server with a private IP address is reachable from the internet. Which NAT configuration should the administrator implement to meet both requirements?
Medium237Which protocol is used to resolve a hostname such as www.example.com into an IP address?
Easy238Which two statements accurately describe DNS in normal network operation?
Medium239What problem does DHCP snooping help prevent?
Medium240Users on the inside network can browse the web, but the company now needs an internal web server at 192.168.10.50 to be reachable consistently from outside using one public IP address. Which design is most appropriate?
Hard241A show ip nat translations command displays this entry: Inside global 203.0.113.10:30001 Inside local 192.168.10.25:51514 Outside local 198.51.100.20:443 Outside global 198.51.100.20:443 Which statement is correct?
Medium242A DHCP client on VLAN 30 is not receiving an IP address from a DHCP server (10.99.99.20) on another subnet. The SVI for VLAN 30 is configured with an IP address and is up, but the DHCP relay command is missing. Which command should be added to the SVI configuration?
Hard243Users on the inside network can browse the Internet through PAT, but an internal web server must now be reachable from outside on a predictable public IP. Which change best fits the requirement?
Hard244Which TWO statements about IPv4 and IPv6 ACLs are true?
Medium245A company wants a server on the inside network to be reachable consistently from outside using one known public IP address. Which NAT approach best fits that goal?
Hard246R1 learns three OSPF routes to different destinations: O 10.10.10.0/24 O IA 10.20.20.0/24 O E2 10.30.30.0/24 Which statement is correct about these route types?
Hard247A switch should disable an edge port immediately if a BPDU is received on it. Which feature is intended for that specific behavior?
Hard248A wireless site reports that users can connect to the SSID, but performance drops sharply around the conference area whenever the room fills up. Based on the exhibit, what is the most likely cause?
Hard249A network administrator is implementing 802.1X port-based authentication on a Cisco switch. The switch will act as the authenticator, and a RADIUS server will provide authentication services. Which two statements are true regarding this deployment? (Choose two.)
Medium250Why is administratively shutting down unused switch ports considered a useful hardening practice?
Hard251A user reports that websites can be opened by IP address but not by hostname. Which service is the strongest suspect?
Medium252Hosts on the inside network can reach the internet, but return traffic is failing after a new router was installed. The router's configuration shows that the LAN-facing interface has been configured with 'ip nat outside' and the WAN-facing interface with 'ip nat inside'. What configuration mistake is the most likely cause?
Hard253Dynamic ARP Inspection is most effective at preventing which attack?
Hard254A router has this command configured: `ip nat inside source static 192.168.1.50 203.0.113.50`. What is the main effect of this configuration?
Hard255Which port-security violation mode drops frames from unauthorized MAC addresses but keeps the interface up and does not send an SNMP trap or syslog message?
Medium256Which three options are true regarding the operation of Dynamic ARP Inspection (DAI) on a Cisco switch? (Choose three.)
Medium257Which TWO statements correctly describe the behavior of standard ACLs when applied to an interface?
Medium258A technician is troubleshooting an issue where internal hosts can successfully ping internet addresses but cannot establish HTTP sessions. The router is configured with PAT (overload) and uses an access list to define the inside local addresses. Recently, the internal network was renumbered from 192.168.0.0/24 to 10.0.0.0/24. What is the most likely cause?
Hard259Based on the exhibit, why is the ACL not meeting the requirement to block only HTTPS traffic to the server?
Hard260Drag and drop the following steps into the correct order to plan, configure, and apply an extended ACL that permits only HTTP traffic from the 192.168.1.0/24 network to the server at 10.0.0.100, and then verify the configuration.
Medium261Why is DHCP often preferred over manual addressing on larger user networks?
Medium262Which TWO statements correctly describe the configuration and verification of AAA with RADIUS/TACACS+ and 802.1X port-based authentication on IOS-XE?
Medium263A network engineer is troubleshooting a Cisco IOS router that should forward DHCP requests from a LAN segment to a centralized DHCP server at 10.1.1.10. The router's LAN interface is GigabitEthernet0/1 with IP address 192.168.20.1/24. The engineer enters the command ip helper-address 10.1.1.10 on interface GigabitEthernet0/1. However, clients on the LAN are not receiving IP addresses. Which condition would cause the DHCP relay to fail?
Hard264A host has a valid IP address and subnet mask from DHCP but cannot reach remote networks because no gateway was provided. What is the best explanation?
Hard265An ACL on R1 contains only these entries: access-list 101 permit tcp 10.10.10.0 0.0.0.255 any eq 443 access-list 101 permit icmp any any What happens to an HTTP packet sourced from 10.10.10.25 and destined for 198.51.100.10 if ACL 101 is applied in the traffic path?
Easy266Drag and drop the following steps into the correct order to configure a Cisco switch as a DHCP relay agent with DHCP snooping, where the DHCP server is located on a remote router.
Medium267Refer to the exhibit. An administrator has configured PAT for internal hosts to access the internet, but users report that they cannot reach external websites. The administrator suspects a NAT issue and runs the show ip nat statistics command. What is the most likely cause of the problem?
Hard268A packet is larger than the outgoing interface MTU and the DF bit is set in the IPv4 header. What should the router do?
Hard269You are connected to R1. Configure DHCP server on R1 to assign addresses from 192.168.50.0/24 to hosts on VLAN 50, excluding 192.168.50.1-192.168.50.20, with default-router 192.168.50.1 and DNS server 8.8.8.8. On switch SW1, configure DHCP snooping globally and on VLAN 50, and enable trusted ports on the uplink to R1. Then, a host on VLAN 50 reports it received an incorrect IP address; troubleshoot and fix the issue: the wrong helper-address is configured on SW1, the excluded range is too large, and a rogue DHCP server is present on port Fa0/5.
Hard270If a host has a valid IP address and subnet mask but no default gateway, what is the most likely result?
Hard271Users in a branch office can reach internal networks but cannot browse the Internet. The router has a correct default route and PAT is configured. Which missing item is the most likely cause if inside hosts are still using private source addresses on the WAN?
Hard272A client receives an IP address but cannot reach remote networks. Which DHCP option is most likely missing or incorrect?
Medium273A company wants unauthorized devices plugged into unused wall ports to have as little chance of gaining access as possible. Which action most directly supports that goal?
Hard274Refer to the exhibit. A network engineer is troubleshooting an ACL that is not filtering traffic as expected. The engineer runs the show access-lists 110 command and notices that all access control entries (ACEs) show zero matches, even though traffic that should match the permit or deny statements is traversing the network. The engineer then checks the interface configuration. What is the most likely cause?
Hard275Why is administratively shutting down unused switch ports considered a useful hardening measure?
Hard276A host at 192.168.50.10/24 needs to send traffic to 192.168.60.20. Which MAC address will it normally place in the Ethernet destination field for the first frame?
Medium277Why is SSH preferred over Telnet for remote device administration?
Medium278Which two statements accurately describe common uses of NTP in network operations?
Medium279A user reports that they cannot access the company's internal web server at 'intranet.company.local' from their workstation. The workstation can ping the web server's IP address 192.168.10.50 successfully, and other internal services like email (mail.company.local) are reachable. Which DNS record issue is most likely causing this problem?
Hard280A branch router should automatically learn the IP address of a time source so logs from all devices show matching timestamps. Which service provides that function?
Easy281A switch should automatically disable any access port that receives a BPDU from an attached device. Which feature directly provides that behavior?
Hard282You are connected to R1. The inside network 192.168.1.0/24 must be able to access the internet using PAT (NAT overload) with the outside interface G0/1 IP 203.0.113.1. Additionally, the internal server at 192.168.1.10 must be reachable from the internet via static NAT to 203.0.113.10. The current configuration is incomplete and contains errors. Identify and fix all issues so that both PAT and static NAT work correctly.
Hard283An administrator wants to permit HTTP and HTTPS from 10.1.10.0/24 to a web server at 198.51.100.20 and deny everything else from that subnet. Which ACL type is required?
Hard284You are connected to R1. Configure R1 as a DHCP server for VLAN 20 clients (192.168.20.0/24) with DNS server 203.0.113.10 and default gateway 192.168.20.1. On switch SW1, enable DHCP snooping globally and on VLAN 20, configure the uplink to R1 as trusted, and ensure that the DHCP server is reachable via ip helper-address on the VLAN 20 SVI. Currently, clients are not receiving IP addresses because of misconfigurations: the excluded-address range on R1 is too large (excluding the entire subnet), the helper-address on SW1 points to a wrong IP (192.0.2.99), and a rogue DHCP server is connected to port Fa0/3 on SW1. Fix all issues so that clients can get addresses securely.
Hard285An operations team wants a monitoring platform to periodically read interface counters and CPU statistics from routers. Which technology is most closely associated with that requirement?
Hard286A network technician is troubleshooting a router that cannot be accessed via SSH. The router responds to Telnet but SSH attempts return 'connection refused'. The technician confirmed that 'ip ssh version 2' is configured and 'show ip ssh' indicates SSH is enabled. The output of 'show line vty 0 4' shows 'transport input telnet'. What should the technician do next?
Hard287A network team is deploying 802.1X on Cisco switches for wired port access control. User laptops run a supplicant that supports EAP-TLS with client certificates, and the company wants mutual authentication between the client and the authentication server. Which component in the 802.1X architecture relays EAP messages between the supplicant and the authentication server while enforcing the port state?
Medium288A network team wants an ACL that permits HTTPS from 10.1.50.0/24 to a web server at 203.0.113.10 and denies all Telnet traffic from that subnet to any destination. Which two ACEs are required?
Medium289A router is configured with PAT for inside users. Which symptom most strongly suggests the NAT inside/outside roles are reversed on the interfaces?
Hard290You are connected to R1. The network uses private IP 10.10.10.0/24 on the inside and must reach the Internet via the outside interface G0/1 with public IP 203.0.113.1/29. Configure PAT (NAT overload) so that inside hosts can access the Internet, and also configure a static NAT for the internal server 10.10.10.100 to public IP 203.0.113.2. The current configuration has errors: the inside and outside interfaces are swapped, the ACL is incorrectly defined, and the overload keyword is missing. Fix all issues.
Hard291A network administrator is configuring a Layer 2 EtherChannel between two switches. Switch A uses 'channel-group 1 mode active', and Switch B uses 'channel-group 1 mode desirable'. All member interfaces are trunk ports with identical allowed VLANs. The EtherChannel fails to form. What is the most likely cause?
Hard292Which four of the following are true statements regarding the operation of DHCP snooping on a Cisco switch? (Choose all that apply. There are four correct answers.)
Medium293A small office has an internal server at 192.168.1.50 that must be reachable from the internet on TCP port 443 using the public address 203.0.113.10. The edge router already performs NAT overload for outbound client traffic on its outside interface. Which configuration correctly adds inbound reachability without breaking existing outbound translation?
Easy294Exhibit: Users on the inside network can open connections to a web server in the DMZ, but return traffic is denied by an ACL on the outside interface. Which statement best explains the issue?
Hard295In AAA, which function determines what an authenticated user is allowed to do after login?
Easy296After enabling DHCP snooping on VLAN 10, a technician finds that clients in that VLAN are no longer receiving IP addresses from the DHCP server. The server is connected to port Gi0/24. What is the most likely cause?
Hard297You are connected to SW1, a multilayer switch. Configure DHCP snooping and an IP helper-address so that clients in VLAN 20 receive IP addresses from the DHCP server at 10.0.0.2. The DHCP server is already configured with a pool for 192.168.20.0/24, but clients are not getting addresses. Identify and correct the issues in the current configuration.
Hard298A network administrator at a small branch office needs to allow a wireless guest user to reach an internal web server at 10.5.5.20 using a browser, while preventing that guest from reaching any other internal subnet. The guest is connected to VLAN 50 and the web server is in VLAN 10. Which type of ACL should be applied on the router between VLANs to meet this requirement?
Easy299A network team wants to collect flow-level traffic statistics from routers to identify top talkers and bandwidth consumers. Which two statements about NetFlow are correct?
Medium300Drag and drop the following steps into the correct order to configure a Layer 3 switch to perform DHCP relay agent and DHCP snooping for a remote DHCP server.
Medium301Which protocol is preferred over Telnet for remote CLI management because it encrypts the session?
Easy302A PC in VLAN 30 must obtain an address from a DHCP server in VLAN 99. Which feature is required on the Layer 3 interface for VLAN 30?
Medium303A branch office uses PAT overload on the edge router. Inside users can reach the internet, but return traffic for a newly deployed server must be mapped to a specific inside host. Which two statements are correct?
Medium304A user can reach a remote web server by IP address but not by hostname. Which service should be checked first?
Medium305Refer to the exhibit. Users on the inside network can browse the web, but return traffic is failing for some sessions. A partial configuration shows: interface GigabitEthernet0/0 ip address 192.168.10.1 255.255.255.0 ip nat outside ! interface GigabitEthernet0/1 ip address 203.0.113.10 255.255.255.0 ip nat inside ! ip nat inside source list 1 interface GigabitEthernet0/1 overload access-list 1 permit 192.168.10.0 0.0.0.255 Based on this configuration, which change is required to make PAT work correctly?
Medium306Which four of the following are characteristics or functions of a stateless firewall, such as an extended access control list (ACL) on a Cisco router? (Choose four.)
Medium307Exhibit: A branch router receives time from an NTP server, but the show output marks the server with a tilde instead of an asterisk. What does that mean?
Medium308A network administrator has configured 802.1X port-based authentication on a Cisco IOS-XE switch port connected to a single PC. The port is in the 'authorized' state, but the PC cannot reach any network resources beyond its directly connected switch. The switch is configured to use RADIUS for authentication. What is the most likely cause of this issue?
Hard309An engineer applies an extended named ACL to a router interface with the ip access-group command but notices that it is filtering traffic in the wrong direction relative to the requirement. The ACL is named EDGE_FILTER and is intended to control packets arriving from the internet. Which command correctly applies the ACL to the outside interface to meet this requirement?
Hard310Why is Telnet generally discouraged for network device administration?
Easy311You are connected to R1 via the console. R1's GigabitEthernet0/0 (192.168.1.1/24) connects to the management network, and GigabitEthernet0/1 (10.0.0.1/30) connects to the core. You need to restrict SSH access to R1 from only the management subnet 192.168.1.0/24. Additionally, SSH should be configured with a domain name 'example.com' and a modulus of 2048 bits. The username 'admin' with password 'Cisco123' should be created for SSH login.
Hard312You are troubleshooting DNS resolution issues from R1. Using nslookup and dig commands, diagnose why the router cannot resolve the hostname 'fileserver.courseiva.com' to an IP address, and why reverse lookup for IP address 198.51.100.10 fails. Determine the appropriate fix to ensure successful forward and reverse DNS resolution.
Hard313A branch office uses PAT for user Internet access. The administrator notices that inside users can browse out, but an internal server still cannot be reached consistently from outside. Which change is most appropriate?
Hard314Why is shutting down unused switch ports considered a useful hardening measure?
Hard315Select the options that correctly pair the security principle or control with its meaning.
Medium316Which of the following is the correct order to plan, configure, and apply an extended ACL that blocks Telnet traffic from the 192.168.1.0/24 network to the 10.0.0.0/24 network, applied inbound on the router's G0/0 interface?
Medium317Which three of the following are security best practices for implementing AAA on a Cisco router? (Choose three.)
Medium318A network engineer is configuring a Cisco switch port for a conference room wall jack. The port must allow only one MAC address at a time, and if a different device is connected, the port should drop packets from the new device but still send a syslog message and increment the violation counter. Which port security violation mode meets these requirements?
Medium319Which two statements accurately describe good management-plane security practice on network devices?
Medium320Users on VLAN 20 are not receiving IPv4 addresses from the centralized DHCP server at 10.50.0.10. Users in other VLANs are working normally. Based on the exhibit, which change should fix the issue for VLAN 20 clients?
Medium321Two switches are configured to form an EtherChannel, but the bundle never comes up. Which explanation best describes this scenario?
Medium322A network team wants visibility into which flows are consuming the most bandwidth between internal subnets. Which technology is most directly associated with that goal?
Hard323A network administrator is troubleshooting an issue where hosts in the 192.168.20.0/24 subnet cannot reach the Internet, while hosts in 192.168.10.0/24 can. The router is configured for PAT overload using a dynamic pool on the outside interface. The administrator collects the configuration shown in the exhibit. What is the most likely cause of the connectivity problem for the 192.168.20.0/24 subnet?
Hard324Which two statements accurately describe the purpose of least privilege in administration and operations?
Medium325An engineer applies this command on an access interface connected to a user PC: switchport port-security violation restrict. What happens if a second unauthorized MAC address appears on the port?
Medium326You are connected to R1 via the console. R1's GigabitEthernet0/0 (10.0.0.1/30) connects to ISP router, and GigabitEthernet0/1 (192.168.1.1/24) connects to the internal LAN. The internal network uses 192.168.1.0/24 and needs to access the internet. Configure NAT overload on R1 so that internal hosts are translated to the IP address of GigabitEthernet0/0 when accessing the internet.
Medium327A network engineer is configuring a Cisco IOS router that connects a small branch office to the Internet. The router's outside interface is GigabitEthernet0/0 with IP address 203.0.113.5/30, and the inside interface is GigabitEthernet0/1 with IP address 192.168.10.1/24. The branch has 50 internal hosts that need simultaneous outbound Internet access, but the ISP assigned only the single public address 203.0.113.5. The engineer wants to conserve public addresses and ensure that internal addresses are hidden. Which configuration should be applied on the router?
Medium328A network engineer notices that after removing a standard ACL that was applied inbound on the internet-facing interface, the router is now receiving IP packets from the internet with source IP addresses in the 10.0.0.0/8 range, which were previously blocked. What is the most likely cause?
Hard329You are connected to R1. The inside network 192.168.10.0/24 must be able to reach the Internet via PAT (NAT overload) using the outside interface G0/1 with IP 203.0.113.2/30. Additionally, the internal server at 192.168.10.100 must be statically mapped to public IP 203.0.113.10. The current configuration is incomplete and contains errors. Fix the NAT configuration on R1 so that both requirements are met.
Hard330Exhibit: Hosts on the inside network can reach the internet, but inbound connections to a published web server fail. Static NAT is configured. What is the most likely missing piece?
Hard331A company wants an internal web server to be reachable consistently from the Internet using one known public IPv4 address. Which NAT approach best fits that requirement?
Hard332A network operations team wants centralized logging from routers and switches and also wants meaningful severity filtering. Which two statements about syslog are correct?
Medium333Which security concept is most closely associated with ensuring data has not been altered in an unauthorized way?
Medium334A team wants to know which internal hosts are sending the most traffic to a specific data center subnet. Which technology is most directly associated with that visibility goal?
Medium335Match each HTTP method to its common REST API action.
Easy336Drag and drop the following steps into the correct order to configure AAA with a RADIUS server and enable 802.1X port authentication on a Cisco IOS-XE switch.
Medium337An engineer wants users to get fast link-up on access ports but also wants the switch to disable a port if another switch is connected and sends BPDUs. Which combination of features best meets that requirement?
Medium338A router performing PAT is using a single public IPv4 address for many inside hosts. Which value most often distinguishes one inside flow from another on the same outside address?
Hard339Exhibit: A network engineer wants to identify which applications are consuming most WAN bandwidth over time. Which feature should be enabled on the router?
Medium340A small office uses PAT for user Internet access. What mechanism does PAT use to allow many users to share one public address while keeping their sessions distinct?
Hard341A DHCP server is located on a different VLAN from the clients. Which feature is required so the clients can still receive addresses?
Medium342Drag and drop the following steps into the correct order to configure and apply an extended ACL that permits only HTTP traffic from the 192.168.1.0/24 network to the server at 10.0.0.1, with the ACL applied inbound on the router's GigabitEthernet0/0 interface, and then verify the configuration.
Medium343Which term in the CIA triad refers to ensuring systems and data remain accessible when needed?
Medium344R1 receives an OSPF route to 10.55.0.0/16 and already has a static route to 10.55.10.0/24. Which route will be used for traffic sent to 10.55.10.25?
Medium345Which STP role identifies the port on a non-root switch that has the best path back to the root bridge?
Easy346A standard ACL and an extended ACL are both available for a design. Which requirement most strongly indicates that an extended ACL is needed?
Hard347Why is the combination of strong authentication and centralized logging generally better than using either one alone?
Hard348You are connected to R1, a multilayer switch acting as a DNS client and DNS server for the local network. The network uses 192.168.1.0/24 for internal hosts. Users report that hostnames like 'server1.example.com' fail to resolve. Diagnose and fix the DNS resolution issue using nslookup and dig. Ensure that R1 can resolve both forward and reverse DNS queries correctly.
Hard349A branch router is acting as a DHCP server. Which two parameters can it provide directly to clients through DHCP?
Medium350An administrator needs to configure an ACL to block HTTP traffic from subnet 10.10.10.0/24 to the web server at 172.16.1.10 while permitting all other traffic. Which ACL entry should be placed first?
Hard351An administrator wants to prevent a specific subnet from using Telnet to reach network devices, while still allowing SSH from that same subnet. What is the strongest reason a standard ACL is not enough by itself?
Hard352Which NAT design is most appropriate when many inside users need outbound Internet access through one public IPv4 address, but no inbound server publishing is required?
Hard353A switch shows a clock that is several minutes off from other devices even though an NTP server has been configured. Which issue is the most likely cause?
Hard354Users on a new access switch can reach devices in their own VLAN but cannot reach the default gateway on the distribution switch. Based on the exhibit, what is the most likely cause?
Medium355An engineer wants remote administrative access to remain available but also wants session contents protected in transit. Which management choice best supports that goal?
Hard356A network engineer notices that internal hosts (192.168.1.0/24) can reach external servers on the internet, but replies from external servers never reach the internal hosts. The router R1 is configured with dynamic NAT to translate the internal subnet to a pool of public IPs (203.0.113.10-203.0.113.20). The engineer runs 'show ip nat translations' and sees only a few stale translations. What is the most likely cause of the issue?
Hard357A network administrator configures PAT on a router to allow internal hosts in the 10.10.10.0/24 subnet to access the Internet. Afterward, users report that they can ping public IP addresses but cannot access any websites. The administrator verifies that the access list for NAT matches the correct subnet, and the 'ip nat inside source list 1 interface GigabitEthernet0/1 overload' command is applied. What is the most likely cause of this issue?
Hard358Why is multifactor authentication generally stronger than password-only access?
Medium359Match each NAT term to its most accurate description.
Medium360Which two features commonly strengthen access-switch security for user-facing ports? (Choose two.)
Medium361A monitoring system already collects Syslog and SNMP data. The network team now wants visibility into which applications or host conversations are driving link utilization. What is the strongest addition?
Hard362Which two statements accurately describe DHCP?
Medium363As a general rule, where should an extended ACL be placed?
Medium364A router is configured for PAT using the WAN interface address. Which command element is most directly associated with allowing many internal users to share that single outside address?
Hard365Exhibit: Users report no internet access after PAT was configured. The inside and outside interfaces are marked correctly. Which missing configuration is the most likely cause?
Hard366Drag and drop the following steps into the correct order to configure and apply an extended IPv4 ACL on a Cisco router to block Telnet traffic from subnet 192.168.1.0/24 to host 10.0.0.1 and permit all other IP traffic.
Medium367A company wants internal users to share one public IPv4 address for outbound Internet access, while keeping sessions separate. Which NAT approach best meets that requirement?
Hard368A network administrator wants to secure remote CLI access to a Cisco router, moving beyond simple username/password authentication. Which approach best achieves this goal?
Medium369You are connected to R1. The network uses a single router with two subnets: 192.168.1.0/24 (connected to GigabitEthernet0/0) and 10.0.0.0/30 (connected to GigabitEthernet0/1). Configure an extended named ACL called 'FILTER_HTTP' that permits HTTP traffic (TCP port 80) from the 192.168.1.0/24 subnet to any destination, and includes an explicit deny statement to deny all other IP traffic. Apply the ACL inbound on GigabitEthernet0/0. Then verify that HTTP traffic is allowed and all other traffic is blocked.
Hard370Based on the exhibit, why is the ACL blocking more traffic than intended?
Hard371Exhibit: An engineer wants a device to send only warning messages and more critical events to a syslog server. Which logging level should be configured?
Medium372Which two statements accurately describe the value of source restriction on administrative access?
Medium373A network administrator notices that syslog messages from a core router are arriving at the syslog server with timestamps that are hours behind other devices. The router’s NetFlow exports also show incorrect start and end times for flows, making traffic analysis unreliable. The administrator verifies that all router interfaces are up and that the SNMP community strings on the router match the NMS.
Hard374Why does DNS make networks easier for people to use?
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Frequently asked questions
- What does the Network Services and Security domain cover on the 200-301 exam?
- You must configure and verify DHCP relay, DHCP snooping, NAT, and ACLs on Cisco IOS, and read exhibits to isolate the broken service. The single most important thing: match each feature to the correct interface and direction, because misplaced ip helper-address, NAT inside/outside, or ACL application causes the exact failures shown.
- How many questions are in this domain?
- This page lists all 374 Network Services and Security questions in the 200-301 question bank. The actual exam draws from this domain proportionally to its weighting in the official exam blueprint.
- What is the best way to practise this domain?
- Start with a short focused session (10 questions) to identify gaps, then work through explanations. Repeat with a longer session once the weak areas feel solid.
- Can I practise only Network Services and Security questions?
- Yes — the session launcher on this page filters questions to this domain only. Choose any session length for inline explanations and scoring.