CCNA Network Services Security Questions

WEP is deprecated and insecure because it uses weak RC4 encryption with static keys, which attackers can easily crack, making it unsuitable for modern enterprise WLANs.

WPA improves on WEP by introducing TKIP but still uses weaker encryption than WPA2 with AES, so it is not the strongest choice for enterprise wireless security.

Open authentication provides no encryption or authentication, leaving wireless traffic exposed to interception and unauthorized access, so it is not a secure method.

The specific factual error is that the existing ACL contains a permit ip any any statement that would override any specific denies, allowing all traffic.

The specific factual error is that ACLs should be applied inbound on the interface where the traffic enters the router, not on the outbound interface towards the destination.

The specific factual error is that outbound ACLs filter traffic exiting the interface, but the traffic from LAN to server enters the router via GigabitEthernet0/0 and exits via another interface (e.g., WAN). An outbound ACL on GigabitEthernet0/0 would not affect traffic going to the server.

STP (Spanning Tree Protocol) is unrelated to hostname resolution. It prevents Layer 2 switching loops and does not affect IP connectivity or DNS services, so it cannot cause hostname resolution failures.

PAT (Port Address Translation) manages IP address translation for outbound traffic but does not handle hostname-to-IP translation. If PAT were failing, IP connectivity itself would be affected, not just hostname resolution.

Port security controls access to switch ports by limiting which MAC addresses can connect. It does not perform or affect hostname resolution or IP address translation, so it is not related to the problem.

IPv6 extension headers are used for additional functionality in IPv6 packets, such as fragmentation or security, and are not involved in NAT overload (PAT) which operates at Layer 4 using port numbers.

Source MAC addresses are used for Layer 2 forwarding within a local network and are not preserved across a router's WAN interface; NAT operates at Layer 3 and above, not using MAC addresses for translation.

Routers do not maintain separate routing tables per client; routing tables are based on destination networks, not individual hosts. NAT overload uses a single routing table and relies on port numbers for translation.

The wildcard mask 255.255.255.0 would match only the exact host 192.168.10.0, not the entire /24 subnet. Cisco ACLs use wildcard masks where 0 means match and 1 means ignore; for a /24, the correct mask is 0.0.0.255.

Standard ACLs can only filter based on source IP address and cannot match specific protocols like Telnet (TCP port 23) or destination addresses. Extended ACLs are required to filter Telnet traffic from a specific source to a specific destination.

PAT (Port Address Translation) is unrelated to ACL filtering. ACLs operate independently of NAT/PAT; they filter traffic based on Layer 3 and Layer 4 information regardless of whether translation is configured.

Fragmenting the packet despite the DF bit being set violates the sender's explicit instruction to avoid fragmentation. Routers must respect the DF bit and cannot fragment in this case.

Routers do not convert IPv4 packets to IPv6 to handle MTU or fragmentation issues. These are different protocols, and such conversion is not a standard router behavior.

Routers do not broadcast oversized packets to other routers for fragmentation. The forwarding decision and fragmentation handling are local to the router, so the packet is dropped if it cannot be forwarded.

The relay address 192.168.100.10 is correctly configured to point to the DHCP server on VLAN 100. The issue is not with the relay address being incorrect.

The DHCP server is on the same router (VLAN 100 interface) and is reachable; the relay configuration is correct. The server is not unreachable.

The exhibit shows 'ip helper-address 192.168.100.10' is configured on GigabitEthernet0/1, which is the VLAN 200 interface. The command is present.

This option is incorrect because advertising Layer 3 reachability is the role of routing protocols like OSPF or EIGRP, not NTP, which only synchronizes time.

This option is incorrect as NTP does not encrypt data traffic by default; it is a time synchronization protocol and does not provide encryption services.

Option A incorrectly identifies the inside global address as the private IP address assigned to the internal PC. This is actually the inside local address, which is the private IP used within the internal network and not visible externally.

Option C confuses the inside global address with outside local or outside global addresses, which refer to remote servers or external hosts from the internal perspective. The inside global address specifically represents the internal PC externally.

Option D incorrectly associates the inside global address with the MAC address of the outside interface. NAT translation deals with IP addresses and ports, not MAC addresses, so this option is invalid.

Telnet transmits credentials and data in plaintext, so it lacks confidentiality and is less secure than SSH.

SSH can be configured on routers, Layer 3 switches, and any device that supports IP connectivity, not just Layer 2 switches.

Blocking Telnet only disables unencrypted remote access; AAA functions (e.g., authentication, authorization, accounting) remain operational via SSH or other methods.

The ip helper-address must be configured on the interface that receives the client broadcasts (VLAN 20), not the server's VLAN.

This command enables relay agent information insertion, not the actual forwarding of DHCP packets to a server.

The question states the DHCP server is at 192.168.10.100, so R1 should relay, not serve.

The default-router option (option 3) provides the gateway for off-subnet traffic. While a missing gateway would prevent access to external networks, the scenario states users receive correct subnet addresses and can likely reach local resources. The inability to browse by hostname points to a DNS issue, not a routing problem.

The lease time option (option 51) determines how long a client can use an assigned IP address before renewing. It does not affect DNS resolution or hostname browsing. A missing or incorrect lease time would cause IP address expiration issues, not name resolution failures.

The TFTP server option (option 66) is used for booting devices like IP phones or diskless workstations to download configuration files or operating systems. It is not involved in hostname resolution. A missing TFTP server would not affect DNS lookups.

Tokens are used for authentication and authorization in API requests, not for converting HTTP requests into SNMP traps. SNMP traps are asynchronous notifications sent by network devices, and token-based APIs operate at a different layer and protocol.

Token-based authentication is unrelated to controller cluster election. Cluster election typically uses protocols like VRRP, HSRP, or proprietary mechanisms to determine an active controller, not API tokens.

Token inclusion in API requests serves authentication and authorization, not data compression. JSON payload compression is typically handled by content-encoding headers (e.g., gzip) and is independent of token usage.

Standard ACLs filter only on source IP, so placing them close to the source can block traffic destined to other networks that should be allowed. The correct placement is close to the destination to minimize unintended filtering.

Standard ACLs do not examine destination IP addresses; they only match on source IP addresses. Filtering by destination requires an extended ACL.

Standard ACLs operate at Layer 3 and cannot examine Layer 4 information such as TCP or UDP port numbers. Port-based filtering requires an extended ACL.

The already-configured ACL permits all IP traffic, so explicitly allowing port 443 would not resolve a server not listening on that port. This step wastes time on a verified configuration.

Static NAT does not use dynamic overload entries. There are no conflicting entries because NAT overload is not configured, making this check irrelevant.

The fact that port 80 works shows the inside global IP is correct. Re-verifying it would not explain the port-specific failure, as the issue is not with the translation.

The ACL must match the source subnet of the inside hosts that need translation; using 192.168.2.0/24 does not match 192.168.1.0/24.

The 'overload' keyword is essential for PAT; omitting it means only one inside host can use the outside IP at a time.

NAT requires one interface to be 'inside' and the other 'outside'; having both as 'inside' prevents translation of outbound traffic.

Standard ACLs filter only on source IP address, so placing them close to the source can block traffic that should be allowed to other destinations, causing unnecessary denial of service.

A wildcard mask of 255.255.255.255 means 'ignore all bits,' so it matches any IP address, equivalent to the 'any' keyword. It does not match all bits.

Extended ACLs are more effective when placed near the source to filter unwanted traffic early, not near the destination. Placing them near the destination allows unwanted traffic to traverse the network unnecessarily.

Increasing the syslog severity threshold to debugging generates more log messages but does not address the root cause of time discrepancies. It can overwhelm storage and analysis without fixing the time synchronization issue.

Disabling console logging reduces output to the console but does not affect the timestamps on logs stored elsewhere. The underlying time synchronization issue remains unresolved.

Clearing the logging buffer removes existing log entries but does not prevent future timestamps from being incorrect. The time drift persists, so new logs will still have mismatched timestamps.

The `ip helper-address` command is configured on the client-facing interface, not the server-facing interface.

The command does not forward all UDP broadcasts; it only forwards specific UDP ports (DHCP, DNS, TFTP, etc.) by default.

The command does not validate source MAC addresses or prevent DHCP spoofing; it only relays DHCP messages.

Bulk backup traffic is throughput-sensitive but not delay-sensitive. It can tolerate delays and jitter without impacting the backup process, so it is not typically prioritized by QoS in Cisco networks.

Email attachments are not time-sensitive and can tolerate delays and jitter. They do not require prioritization in QoS policies, making this option incorrect for delay-sensitive traffic.

Operating system updates involve large data transfers that are throughput-sensitive but not sensitive to delay or jitter. They are usually scheduled during off-peak times and are not prioritized by QoS.

Standard ACLs can only filter based on source IP address, not destination ports or protocols. They lack the granularity to distinguish between Telnet and SSH traffic.

Extended ACLs are not required for every router login policy; they are only needed when filtering must consider protocol or port information. Simple source-based filtering can use standard ACLs.

SSH uses TCP port 22, while Telnet uses TCP port 23. They are distinct ports, so an ACL can differentiate them based on destination port.

The specific factual error: The inside/outside interface assignment is reversed; ACL 10 permits 10.0.0.0/8 instead of 192.168.1.0/24.

The specific factual error: The inside/outside interface assignment is reversed; the WAN interface should be outside, not inside.

The specific factual error: The 'overload' keyword is missing, which is required for PAT to enable many-to-one translation.

This option is incorrect because neither least privilege nor source restriction eliminates the need for logging; visibility and accountability remain critical for security auditing.

This option is incorrect because least privilege and source restriction are broad security principles applicable to all administrative access, not limited to wireless guest access policies.

This option is incorrect because PPP encapsulation is unrelated to administrative access controls like least privilege and source restriction; it does not affect management access security.

Increasing the TTL value of voice packets is unrelated to QoS or priority queuing. TTL controls packet lifetime and does not affect delay or jitter, so this option is incorrect.

QoS does not convert RTP (used for voice) into TCP. RTP is typically carried over UDP for real-time performance, so this option is incorrect.

Assigning IP addresses to phones is handled by DHCP or static configuration, not by QoS or priority queuing. This option is unrelated to voice traffic prioritization.

This statement incorrectly associates two separate features; DHCP snooping operates at Layer 2 for DHCP security, not for CDP.

This function belongs to the relay agent, not to DHCP snooping, which operates within a single VLAN to enforce security policies.

This is a relay agent feature; DHCP snooping does not alter the broadcast nature of DHCP packets, it only filters them.

The static NAT entry is correct; the inside address 192.168.10.100 is properly mapped to 203.0.113.5.

Static NAT requires a separate public IP to avoid overlapping with PAT translations. The public IP 203.0.113.5 is appropriate.

The static NAT entry is correctly configured with 192.168.10.100 and 203.0.113.5; the error is solely in the ACL and missing overload keyword.

Option C is incorrect because DNS does not assign IP addresses; that task belongs to DHCP, which dynamically provides IP configuration to hosts on a network.

Option D is incorrect because DNS does not replace subnet masks; subnet masks are used to define network and host portions of an IP address and control routing and addressing scope.

Option E is incorrect because DNS has no role in Spanning Tree Protocol (STP) operations, such as electing the root bridge; these functions are unrelated to DNS.

Candidates may think that an empty binding table means the service is off, but the command itself would fail or show a service status if DHCP were truly disabled.

Candidates often associate 'no addresses assigned' with a pool misconfiguration, but a pool mismatch would not prevent the server from seeing DISCOVER messages and possibly creating failed or erroneous bindings.

Candidates may confuse a missing option with a complete failure of DHCP operation, but IP address leasing is independent of options like default-router.

The deny ip any any statement overrides the permit statements because ACLs are processed sequentially; any packet matching the deny is dropped. Also, applying the ACL inbound on the server-facing interface would filter traffic coming from the servers, not from the 192.168.1.0/24 subnet.

The ACL should be applied inbound on the interface receiving traffic from the 192.168.1.0/24 subnet (GigabitEthernet0/0) to filter before routing. Applying it outbound on the same interface would only filter traffic leaving that interface, which is not the traffic path from the subnet to the servers.

The ACL must be applied on the interface closest to the source of the traffic to be filtered. Since the traffic originates from the 192.168.1.0/24 subnet, the ACL should be applied inbound on GigabitEthernet0/0, not on the server-facing interface.

Logs and accounting records do not replace authentication; they complement it by recording who accessed what and when. Authentication is still required to verify identity before access is granted, and logs only capture activity after authentication occurs.

Logging and accounting are essential across all network segments, including wired, wireless, VPN, and data center environments. Limiting them to wireless guest networks would leave other critical areas unmonitored, creating security gaps.

Logs and accounting records are passive records of events; they do not automatically create or modify access policies. Policy creation requires administrative action based on analysis of logs, not the logs themselves.

PortFast is a Spanning Tree Protocol feature that immediately transitions an access port to the forwarding state, bypassing the listening and learning states. It does not inspect or validate DHCP messages, so it cannot prevent a rogue DHCP server from handing out addresses.

HSRP (Hot Standby Router Protocol) provides first-hop redundancy by allowing multiple routers to share a virtual IP address, ensuring gateway availability. It does not inspect DHCP traffic or provide any mechanism to block unauthorized DHCP servers.

LLDP (Link Layer Discovery Protocol) is a vendor-neutral protocol used for discovering neighboring devices and their capabilities by exchanging information such as device type, management addresses, and VLAN IDs. It has no role in DHCP security or filtering DHCP messages.

Candidates may assume any ACL misbehavior is due to wrong interface direction, ignoring that the specific symptom (only 192.168.20.0 is unreachable) points to the deny rule itself.

Candidates often focus on what an ACL ‘lacks’ rather than the sequence, missing that the existing permit any covers the destination but is shadowed by the earlier deny.

Candidates might recall that all ACLs have an implicit deny, but they fail to realize that a packet matching an earlier deny is already discarded, and the implicit deny only applies to unmatched traffic.

PAT works with any transport protocol that has port fields—TCP, UDP, and even ICMP through the identifier field.

Only dynamic translations (from dynamic NAT or PAT) have idle timeouts; static mappings are permanent.

This statement describes dynamic NAT pool exhaustion, not PAT, which uses port multiplexing.

Disabling unused services does not affect routing convergence, which depends on routing protocols and network topology. Service hardening and routing optimization are separate concerns.

Disabling services reduces risk but does not guarantee prevention of misconfiguration; human error can still occur in other settings. Security hardening is a layered approach, not a silver bullet.

Disabling services does not change a device's role; a router remains a router, and a switch remains a switch. Converting a device to a controller requires specific software and configuration changes.

SSH does not eliminate the need for authentication and authorization policies; it only provides a secure transport layer. Network devices still require AAA (Authentication, Authorization, and Accounting) or local username/password configurations to control access.

Telnet is not a prerequisite for SSH; they are independent protocols. SSH can be configured and used on a device without Telnet ever being enabled. In fact, many devices have SSH enabled by default while Telnet is disabled for security reasons.

SSH is not limited to wireless controllers; it is widely used on routers, switches, firewalls, servers, and many other network devices. It is a universal protocol for secure remote administration across all types of infrastructure.

Option B incorrectly permits UDP traffic on port 22, but SSH uses TCP, not UDP, so this rule would not allow SSH connections and is therefore invalid.

Option C permits TCP traffic from any source to the destination host on port 22, which is too broad because it does not restrict access to the specific source host 10.10.10.50 as required.

Option D permits all IP traffic from the source host to the destination host without restricting to TCP or port 22, allowing all protocols and ports, which is not limited to SSH and is too permissive.

The ACL must match the inside network; permitting a different subnet will not translate traffic from the correct LAN.

The NAT inside/outside designation is based on the direction of traffic; the interface facing the public network must be outside.

Without 'overload', the router will not use port numbers to multiplex multiple inside hosts to a single public IP.

NTP (Network Time Protocol) synchronizes clocks across network devices but does not impact the ability to resolve domain names or browse websites. Time synchronization issues rarely cause name resolution failures, so NTP is not the failing component here.

Syslog collects and stores system logs for monitoring and troubleshooting but does not affect DNS resolution or web browsing. A syslog failure would not prevent browsing by hostname, so it is not the cause.

CDP (Cisco Discovery Protocol) is used for discovering directly connected Cisco devices and does not play any role in DNS or web name resolution. CDP failure would not cause inability to browse websites by name.

The specific factual error: The trap level is set too low (informational instead of notifications), and the source interface is incorrect.

The specific factual error: The logging host command is missing the 'host' keyword, and the timestamps command is incomplete.

The specific factual error: The timestamps command applies to debug messages instead of log messages, and the source interface is wrong.

Configuring an access port as a trunk would cause the switch to expect 802.1Q tagging on all frames, but the PC behind the phone typically sends untagged frames. This would break connectivity for the PC unless the phone is configured to tag PC traffic, which is not standard.

The channel-group command is used to create an EtherChannel, which bundles multiple physical links into a single logical link. This is not relevant for a single access port connecting to an IP phone and PC, as there is only one physical link.

The spanning-tree cost command manually sets the STP path cost for a port, which is used for loop prevention. It does not affect VLAN assignment or voice/data separation, so it does not address the requirement of carrying voice and data correctly.

The NAT interface directions are reversed; the internal-facing interface must be 'ip nat inside' and the external-facing interface must be 'ip nat outside'.

Static NAT for services must include the protocol (tcp/udp) and port number to map specific services; otherwise, it maps the entire IP address, which is not desired here.

The 'ip nat outside source static' command is used for translating the source address of inbound packets (e.g., for load balancing), not for mapping a public IP to an internal server. For inbound access to servers, 'ip nat inside source static' is required.

The specific factual error is that the order of entries matters; a deny any any at the end would block all traffic, but here it is placed before the permit, so the deny is evaluated first.

The specific factual error is that standard ACLs lack the capability to filter by protocol or port; extended ACLs are required for such granularity.

The specific factual error is that the permit statement uses 'any' for source and destination, making it too permissive and not matching the specified networks.

Incorrect because NTP does not convert Syslog into a routing protocol; NTP’s function is strictly time synchronization, unrelated to routing protocols.

Incorrect because NTP does not create DHCP pools; DHCP pool creation is unrelated to time synchronization and is managed by DHCP services.

Incorrect because NTP does not eliminate the need for a Syslog server; it complements Syslog by providing accurate timestamps but does not replace log collection.

STP (Spanning Tree Protocol) prevents loops in redundant topologies and does not block hosts based on IP or MAC address changes. It operates at Layer 2 and is unrelated to IP address configuration.

OSPF is a Layer 3 routing protocol used between routers, not on access ports connecting hosts. OSPF authentication is configured on router interfaces and does not apply to host ARP traffic on a switch.

PPP (Point-to-Point Protocol) authentication is used on serial links or PPPoE connections, not on Ethernet switch ports. It is unrelated to ARP inspection or DHCP snooping in a switched network.

Incorrect because PAT alone cannot provide a stable public IP for inbound connections to a server, making it unsuitable for predictable external access to internal services.

Incorrect because private IPv4 addresses are not routable on the Internet, so disabling NAT would prevent internal hosts from accessing external networks and external clients from reaching internal servers.

Incorrect because DHCP relay is used to forward DHCP requests across networks and does not influence NAT or the public accessibility of internal servers.

NetFlow does not replace routing protocols; it is a monitoring tool that provides traffic statistics, not a path-selection mechanism.

NetFlow operates on routers and Layer 3 switches, not just Layer 2 switches, and is commonly used on routers for traffic analysis.

Uses the keyword 'informational' instead of the required numeric level 6.

Uses 'ntp peer' instead of 'ntp server', and uses numeric levels but the primary command is wrong.

Mixes numeric and keyword severity levels; must use numeric 6 for both console and buffer.

The Ethernet trailer contains a Frame Check Sequence (FCS) for error detection at Layer 2, not application-layer data like bearer tokens. Tokens are part of the HTTP application layer and are never placed in the Ethernet trailer.

DNS responses contain resource records like A, AAAA, or CNAME, which map domain names to IP addresses. They have no role in carrying authentication tokens for REST API calls, as DNS is a separate protocol for name resolution.

The TCP checksum field is used for error detection of the TCP segment header and payload at the transport layer. It is computed by the sender and verified by the receiver; it does not carry any application data such as bearer tokens.

The current DNS server is reachable but lacks the record; simply changing the DNS server to an arbitrary IP would not guarantee resolution unless that server is known to hold the correct record, and there is no indication that 203.0.113.53 is a valid DNS server.

DNS resolution failure is not due to routing: the router can already reach the DNS server. Adding a static route will not fix missing DNS records.

The Google public DNS server likely does not have an entry for the internal hostname fileserver.courseiva.com, so this will not enable resolution.

The show authentication sessions output indicates 'Authz Success', meaning authentication and authorization succeeded. A shared secret mismatch would cause authentication failure, not a successful authorization.

The show command output clearly shows the port status as 'AUTHORIZED' and 'Authz Success'. There is no indication of err-disable. Port-security violations would show a different status, such as 'err-disabled' or 'security-violation'.

The output shows 'authVlan = 100' and the session is authorized with 'method = dot1x' and 'status = AUTHORIZED'. This indicates the supplicant successfully authenticated and was placed in the auth VLAN, not the guest VLAN. If the supplicant had failed, the port would be in the guest VLAN.

Authentication is incorrect because it only verifies the user's identity to allow login; it does not control what commands or modes the user can access after login.

Accounting is incorrect because it only records user activity and command usage for auditing purposes and does not influence login permissions or command access.

DNS is incorrect because it is related to name resolution and does not control user authentication, authorization, or command permissions on network devices.

This distractor exploits the common tendency to blame the helper address configuration first, overlooking the security feature that silently drops the returning DHCPOFFER.

This plays on the misconception that a switch requires an IP address on the client VLAN to facilitate DHCP, when in fact the router acting as the relay agent provides Layer 3 connectivity.

This misinterprets DHCP snooping behavior: it assumes all DHCP traffic is filtered on untrusted ports, overlooking the critical distinction that only server-side messages are blocked, not client requests.