CCNA Mock Exam 82 — 25 Questions

Question 1

You are connected to R1. Configure AAA with RADIUS authentication on R1 so that SSH login attempts first contact the RADIUS server at 192.0.2.10 (key 'cisco123'), and if the server is unreachable, fall back to the local database. Additionally, troubleshoot why an 802.1X-enabled switch port (GigabitEthernet0/1) on a connected switch remains in the 'unauthorized' state despite RADIUS being functional; identify and fix the misconfiguration on the switch (SW1).

Accepted Answer

R1: 'aaa new-model', 'radius server RADIUS', 'address ipv4 192.0.2.10 key cisco123', 'aaa authentication login default group radius local', 'line vty 0 4', 'login authentication default'. SW1: 'aaa new-model', 'radius server RADIUS', 'address ipv4 192.0.2.10 key cisco123', 'aaa authentication dot1x default group radius', 'dot1x system-auth-control', 'interface GigabitEthernet0/1', 'authentication port-control auto', 'dot1x pae authenticator'.. The correct answer is Option A. For R1, the 'aaa authentication login default group radius local' command ensures that SSH login attempts first contact the RADIUS server at 192.0.2.10 and fall back to the local database if the server is unreachable. Options that omit the 'local' keyword (C) lack this fallback, making them incorrect. Option B incorrectly uses 'aaa authentication login' on the switch for 802.1X; the correct command is 'aaa authentication dot1x'. On SW1, all wrong options (B, C, D) are missing the 'dot1x pae authenticator' command under the interface, which is required for the switch to explicitly act as an 802.1X authenticator (though some IOS versions auto-assume it, Cisco CCNA expects explicit configuration). Option D also lacks 'dot1x pae authenticator', leaving the port in unauthorized state. Only Option A includes all necessary commands: correct RADIUS server definitions, proper AAA authentication lists for both login and dot1x, global 'dot1x system-auth-control', and the interface-level commands 'authentication port-control auto' and 'dot1x pae authenticator'.

Answer

R1: 'aaa new-model', 'radius server RADIUS', 'address ipv4 192.0.2.10 key cisco123', 'aaa authentication login default group radius local', 'line vty 0 4', 'login authentication default'. SW1: 'aaa new-model', 'radius server RADIUS', 'address ipv4 192.0.2.10 key cisco123', 'aaa authentication login default group radius', 'dot1x system-auth-control', 'interface GigabitEthernet0/1', 'authentication port-control auto', 'dot1x pae authenticator'.

Answer

R1: 'aaa new-model', 'radius server RADIUS', 'address ipv4 192.0.2.10 key cisco123', 'aaa authentication login default group radius', 'line vty 0 4', 'login authentication default'. SW1: 'aaa new-model', 'radius server RADIUS', 'address ipv4 192.0.2.10 key cisco123', 'aaa authentication dot1x default group radius', 'dot1x system-auth-control', 'interface GigabitEthernet0/1', 'authentication port-control auto', 'dot1x pae authenticator'.

Answer

R1: 'aaa new-model', 'radius server RADIUS', 'address ipv4 192.0.2.10 key cisco123', 'aaa authentication login default group radius local', 'line vty 0 4', 'login authentication default'. SW1: 'aaa new-model', 'radius server RADIUS', 'address ipv4 192.0.2.10 key cisco123', 'aaa authentication dot1x default group radius', 'dot1x system-auth-control', 'interface GigabitEthernet0/1', 'authentication port-control auto'.

Question 2

You 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.

Accepted Answer

Change interface G0/1 to 'ip nat outside', add 'overload' to the dynamic NAT rule, and correct ACL 100 to permit 192.168.1.0 0.0.0.255. The configuration had three issues: (1) Interface G0/1 was incorrectly configured as 'ip nat inside' instead of 'ip nat outside' — this prevents translation as both interfaces are inside. (2) The NAT overload keyword was missing on the dynamic PAT rule — without 'overload', only one-to-one translation occurs. (3) ACL 100 was matching 192.168.2.0/24 instead of the actual inside subnet 192.168.1.0/24, so traffic from the correct subnet was not translated. Correcting these allows inside hosts to PAT to the outside IP and the static NAT to function properly.

Answer

Change interface G0/1 to 'ip nat outside', add 'overload' to the dynamic NAT rule, and change ACL 100 to permit 192.168.2.0 0.0.0.255

Answer

Change interface G0/1 to 'ip nat outside', remove the 'overload' keyword from the dynamic NAT rule, and correct ACL 100 to permit 192.168.1.0 0.0.0.255

Answer

Change interface G0/1 to 'ip nat inside', add 'overload' to the dynamic NAT rule, and correct ACL 100 to permit 192.168.1.0 0.0.0.255

Question 3

You are connected to R1, a Cisco IOS-XE router. The network uses a DNS server at 203.0.113.10 for name resolution. Users report that 'ping server.example.com' fails, but 'ping 203.0.113.50' succeeds. Assume proper routing is configured between R1 and the DNS server. Diagnose and resolve the DNS resolution issue so that the hostname resolves correctly, and verify the fix using appropriate Cisco IOS commands (e.g., ping, show hosts, debug domain).

Accepted Answer

Configure R1 to use a different DNS server, such as 198.51.100.10, that has the correct A record for server.example.com.. The issue is that the DNS server at 203.0.113.10 does not have a valid A record for server.example.com, returning NXDOMAIN. Since ping to the IP address works, connectivity is fine. To resolve, configure R1 to use a different DNS server (e.g., 198.51.100.10) that has the correct A record. After configuration, verify with 'show hosts' to see the resolved hostname entry and 'ping server.example.com' to confirm successful resolution. The options involving DNS cache clearing or enabling domain lookup are irrelevant because the problem lies with the DNS server itself, not with caching or disabled DNS lookup.

Answer

Add the command 'ip domain lookup' under global configuration to enable DNS resolution on R1.

Answer

Clear the DNS cache on R1 using 'clear ip dns cache' to remove any stale entries.

Answer

Configure the router to use the IP address 203.0.113.50 as the DNS server instead of 203.0.113.10.

Question 4

You are connected to R1. The network consists of three routers: R1, R2, and R3. R1's G0/0 connects to R2 (10.0.0.0/30), and R1's G0/1 connects to R3 (10.0.1.0/30). A server at 203.0.113.100 on R2's LAN must be reachable from R3's LAN (203.0.113.0/24) via ICMP, but all other traffic from R3 to R2 must be blocked. The current ACL on R1 is too permissive, allowing all traffic. Configure and apply a standard ACL to permit only ICMP echo requests from R3 to the server, with the implicit deny blocking everything else.

Accepted Answer

Remove ACL 10 from G0/0, delete ACL 10, then configure extended ACL 100 with 'permit icmp 203.0.113.0 0.0.0.255 host 203.0.113.100 echo' and apply it inbound on G0/1.. The current ACL 10 permits all traffic inbound on G0/0, which is too permissive. The requirement is to allow only ICMP echo requests from R3's LAN (source 203.0.113.0/24) to the server at 203.0.113.100. A standard ACL uses source IP only. First, remove the existing ACL from the interface with 'no ip access-group 10 in' on G0/0. Then delete ACL 10 with 'no access-list 10'. Create a new standard ACL that permits ICMP echo requests; since standard ACLs cannot filter by protocol, we must use an extended ACL. So we configure an extended ACL (e.g., 100) with 'permit icmp 203.0.113.0 0.0.0.255 host 203.0.113.100 echo' and apply it inbound on G0/1 (the interface facing R3) to filter traffic before it enters R1. The implicit deny will block all other traffic from R3 to R2.

Answer

Remove ACL 10 from G0/0, delete ACL 10, then configure standard ACL 10 with 'permit 203.0.113.0 0.0.0.255' and apply it inbound on G0/1.

Answer

Remove ACL 10 from G0/0, delete ACL 10, then configure extended ACL 100 with 'permit icmp host 203.0.113.100 203.0.113.0 0.0.0.255 echo' and apply it inbound on G0/0.

Answer

Keep the existing ACL 10 applied inbound on G0/0, but add an extended ACL 100 with 'permit icmp 203.0.113.0 0.0.0.255 host 203.0.113.100 echo' applied inbound on G0/1.

Question 5

You 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.

Accepted Answer

Correct the NAT interface directions: G0/0 as inside, G0/1 as outside. Add 'overload' to the PAT command. Change ACL 100 to permit 192.168.1.0 0.0.0.255.. The configuration had three issues: (1) Inside and outside interfaces were swapped — G0/0 (inside) was marked 'ip nat outside' and G0/1 (outside) was 'ip nat inside'. (2) The PAT command was missing the 'overload' keyword. (3) ACL 100 matched the wrong subnet (192.168.2.0 instead of 192.168.1.0). To fix: correct interface NAT directions, add 'overload', and update ACL to permit 192.168.1.0/24.

Answer

Change the NAT interface directions: G0/0 as outside, G0/1 as inside. Add 'overload' to the PAT command. Change ACL 100 to permit 192.168.1.0 0.0.0.255.

Answer

Correct the NAT interface directions: G0/0 as inside, G0/1 as outside. Add 'overload' to the PAT command. Keep ACL 100 as is because it already permits the correct subnet.

Answer

Change the NAT interface directions: G0/0 as outside, G0/1 as inside. Add 'overload' to the PAT command. Change ACL 100 to permit 192.168.1.0 0.0.0.255.

Question 6

You 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.

Accepted Answer

Add an A record for 'fileserver.courseiva.com' pointing to 198.51.100.10 and a PTR record for 198.51.100.10 pointing to 'fileserver.courseiva.com' on the DNS server.. The DNS resolution failures are due to two issues: the A record for 'fileserver.courseiva.com' does not exist on the DNS server (NXDOMAIN response), and the PTR record for reverse lookup of 198.51.100.10 is missing. To resolve the forward lookup, you must add an A record mapping the hostname to an IP address on the DNS server (e.g., 198.51.100.10). For the reverse lookup, you need to add a PTR record mapping the IP address 198.51.100.10 to the hostname. On R1, the DNS configuration is correct (ip domain-lookup enabled, name-server 203.0.113.1), but the DNS server lacks the necessary records. The solution involves configuring the DNS server (not R1) to add the missing records. On R1, ensure that the DNS server is reachable and that the domain lookup is enabled; no additional CLI changes are required on the router.

Answer

Configure the 'ip host' command on R1 to statically map 'fileserver.courseiva.com' to 198.51.100.10.

Answer

Enable 'ip domain-lookup' and configure the correct DNS server IP on R1 using 'ip name-server 203.0.113.1'.

Answer

Add only an A record for 'fileserver.courseiva.com' on the DNS server.

Question 7

You 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.

Accepted Answer

Configure 'ip nat inside' on GigabitEthernet0/0, 'ip nat outside' on GigabitEthernet0/1, correct ACL 10 to permit 192.168.1.0 0.0.0.255, and add 'overload' to the PAT command.. Three issues exist: (1) The inside and outside interfaces are swapped — GigabitEthernet0/0 (LAN) should be 'ip nat inside' and GigabitEthernet0/1 (WAN) should be 'ip nat outside'. (2) The PAT command lacks the 'overload' keyword. (3) ACL 10 permits 10.0.0.0/8 but the inside subnet is 192.168.1.0/24; ACL must be corrected. Fix with 'interface GigabitEthernet0/0', 'ip nat inside', 'interface GigabitEthernet0/1', 'ip nat outside', 'ip nat inside source list 10 interface GigabitEthernet0/1 overload', and 'access-list 10 permit 192.168.1.0 0.0.0.255'.

Answer

Configure 'ip nat outside' on GigabitEthernet0/0, 'ip nat inside' on GigabitEthernet0/1, keep ACL 10 as is, and add 'overload' to the PAT command.

Answer

Configure 'ip nat inside' on GigabitEthernet0/1, 'ip nat outside' on GigabitEthernet0/0, correct ACL 10 to permit 192.168.1.0 0.0.0.255, and add 'overload' to the PAT command.

Answer

Configure 'ip nat inside' on GigabitEthernet0/0, 'ip nat outside' on GigabitEthernet0/1, correct ACL 10 to permit 192.168.1.0 0.0.0.255, but do not add 'overload' to the PAT command.

Question 8

You are connected to R1 via the console. The network operations center (NOC) has asked you to configure R1 as an NTP client of the NTP server at 192.0.2.10 (reachable via VLAN 100, SVI 192.168.1.1/24). They also need all system messages of level 'debug' (level 7) and higher forwarded to the syslog server at 203.0.113.50. The current configuration shows that NTP is not working (stratum 16) and syslog is only sending critical and higher messages. Fix both issues.

Accepted Answer

Configure 'ntp source Vlan100' and 'logging trap debugging'.. The NTP client is not synchronizing because there is no source interface specified; the NTP packets may be sourced from an unexpected interface and the server may ignore them. The solution is to configure 'ntp source Vlan100' to ensure NTP packets use the correct source IP. Additionally, the syslog trap level is set to 'critical', which filters out messages with severity lower than critical (like warnings, errors, etc.). The NOC requires all messages up to debug level; therefore, change the logging trap level to 'debugging' with 'logging trap debugging'.

Answer

Configure 'ntp server 192.0.2.10' and 'logging trap 7'.

Answer

Configure 'ntp source Vlan100' and 'logging trap warnings'.

Answer

Configure 'ntp update-calendar' and 'logging trap informational'.

Question 9

You 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?

Accepted Answer

Add a static host entry: ip host fileserver.courseiva.com 203.0.113.10. The DNS server is reachable but does not have an A record for fileserver.courseiva.com, so NXDOMAIN is returned. The router can resolve the name locally by adding a static host entry with `ip host`. This bypasses the external DNS and directly maps the hostname to the correct IP. Changing the DNS server to another unknown IP does not guarantee resolution, and static routes or external public DNS are irrelevant for this internal name.

Answer

Change the DNS server to 203.0.113.53 using the command 'ip name-server 203.0.113.53'

Answer

Add a static route to 198.51.100.53 via the next-hop interface

Answer

Configure the router to use the DNS server at 8.8.8.8 using 'ip name-server 8.8.8.8'

Question 10

You 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.

Accepted Answer

Configure 'ip name-server 203.0.113.10' under global configuration and ensure the DNS server has an A record for www.example.com pointing to 203.0.113.100.. The issue is that the DNS server IP address configured under 'ip name-server' is incorrect (10.0.0.2) instead of the actual DNS server (203.0.113.10). Additionally, the DNS server itself is not configured with the proper A record for www.example.com. The fix involves correcting the name-server address and ensuring the DNS server has the correct forward mapping. After correcting the name-server, nslookup and dig should return the IP address 203.0.113.100. For reverse lookup, a PTR record for 203.0.113.100 pointing to www.example.com must exist on the DNS server.

Answer

Configure 'ip domain-lookup' and 'ip name-server 10.0.0.2' under global configuration, then verify with ping www.example.com.

Answer

Configure 'ip domain-lookup' and 'ip host www.example.com 203.0.113.100' under global configuration, then verify with ping www.example.com.

Answer

Configure 'ip dns server' under global configuration to make R1 act as a DNS server, then add an A record for www.example.com.

Question 11

You 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.

Accepted Answer

interface GigabitEthernet0/1
ip nat outside
!
access-list 1 permit 192.168.1.0 0.0.0.255
!
ip nat inside source list 1 interface GigabitEthernet0/1 overload
ip nat inside source static 192.168.1.10 203.0.113.10. The configuration has three issues: 1) GigabitEthernet0/1 is incorrectly set as 'ip nat inside' instead of 'ip nat outside'. 2) The PAT command is missing the 'overload' keyword. 3) Access-list 1 permits 10.0.0.0/8, not the inside subnet 192.168.1.0/24. The commands fix these: change the interface to 'ip nat outside', add 'overload' to the PAT command, and update the ACL to permit the correct inside network.

Answer

interface GigabitEthernet0/1
ip nat inside
!
access-list 1 permit 192.168.1.0 0.0.0.255
!
ip nat inside source list 1 interface GigabitEthernet0/1 overload
ip nat inside source static 192.168.1.10 203.0.113.10

Answer

interface GigabitEthernet0/1
ip nat outside
!
access-list 1 permit 10.0.0.0 0.255.255.255
!
ip nat inside source list 1 interface GigabitEthernet0/1
ip nat inside source static 192.168.1.10 203.0.113.10

Answer

interface GigabitEthernet0/1
ip nat outside
!
access-list 1 permit 192.168.1.0 0.0.0.255
!
ip nat inside source list 1 interface GigabitEthernet0/1 overload
ip nat inside source static tcp 192.168.1.10 80 203.0.113.10 80

Question 12

You are connected to R1. Configure SNMPv3 with authentication (SHA) and encryption (AES-128) for user 'monitor' in group 'AdminGroup', and also configure SNMPv2c read-only community string 'cisco123' to send traps to the management server at 192.0.2.100. Additionally, configure NetFlow on interface GigabitEthernet0/0 to export flow data to 198.51.100.50 using version 9. Verify your configuration using the appropriate show commands.

Accepted Answer

snmp-server group AdminGroup v3 priv read AdminView; snmp-server user monitor AdminGroup v3 auth sha cisco123 priv aes 128 cisco123; snmp-server community cisco123 ro; snmp-server host 192.0.2.100 traps version 2c cisco123; interface GigabitEthernet0/0; ip flow-export destination 198.51.100.50 9996; ip flow-export version 9; ip flow ingress. The configuration was missing SNMPv3 user, group, and trap settings. We added the SNMPv3 user 'monitor' with SHA authentication and AES-128 encryption, created a view and group 'AdminGroup' with read access, and configured the SNMPv2c community string 'cisco123' for read-only access. We also enabled SNMP traps to the manager at 192.0.2.100 and configured NetFlow on GigabitEthernet0/0 to export to 198.51.100.50 using version 9. Verification commands show the SNMP configuration and NetFlow flow cache.

Answer

snmp-server group AdminGroup v3 auth read AdminView; snmp-server user monitor AdminGroup v3 auth sha cisco123 priv aes 128 cisco123; snmp-server community cisco123 ro; snmp-server host 192.0.2.100 traps version 2c cisco123; interface GigabitEthernet0/0; ip flow-export destination 198.51.100.50 9996; ip flow-export version 9; ip flow ingress

Answer

snmp-server group AdminGroup v3 priv read AdminView; snmp-server user monitor AdminGroup v3 auth sha cisco123 priv des 56 cisco123; snmp-server community cisco123 ro; snmp-server host 192.0.2.100 traps version 2c cisco123; interface GigabitEthernet0/0; ip flow-export destination 198.51.100.50 9996; ip flow-export version 9; ip flow ingress

Answer

snmp-server group AdminGroup v3 priv read AdminView; snmp-server user monitor AdminGroup v3 auth sha cisco123 priv aes 128 cisco123; snmp-server community cisco123 ro; snmp-server host 192.0.2.100 traps version 2c cisco123; interface GigabitEthernet0/0; ip flow-export destination 198.51.100.50 9996; ip flow-export version 5; ip flow ingress

Question 13

You 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.

Accepted Answer

Remove the unreachable DNS server 192.0.2.53, add an A record for webserver.internal (192.168.10.50), and correct the PTR record for 192.168.10.50 to point to webserver.internal.. The DNS server 192.0.2.53 is unreachable, causing timeouts for external queries. The primary DNS server 203.0.113.53 returns NXDOMAIN for 'webserver.internal' because no A record exists for that hostname in the internal zone. Additionally, the PTR record for 192.168.10.50 incorrectly points to 'mail.internal' instead of 'webserver.internal'. To fix, first remove the unreachable DNS server with 'no ip name-server 192.0.2.53' or replace it with a reachable one. Then, on the DNS server (or via static host entries on R1), add an A record for webserver.internal (192.168.10.50) and correct the PTR record to point to webserver.internal. Optionally, configure 'ip host webserver.internal 192.168.10.50' on R1 for local resolution.

Answer

Add an A record for webserver.internal (192.168.10.50) and correct the PTR record for 192.168.10.50 to point to webserver.internal, but leave the unreachable DNS server 192.0.2.53 in the configuration.

Answer

Remove the unreachable DNS server 192.0.2.53 and add an A record for webserver.internal (192.168.10.50), but do not correct the PTR record for 192.168.10.50.

Answer

Replace the unreachable DNS server 192.0.2.53 with a reachable one, and correct the PTR record for 192.168.10.50 to point to webserver.internal, but do not add an A record for webserver.internal.

Question 14

You are connected to R1, a branch router connected to a central NTP server at 203.0.113.10 and a syslog server at 198.51.100.20. Configure R1 as an NTP client using its Loopback0 interface (192.168.1.1/32) as the source, and ensure syslog messages of severity 'informational' and above are sent to the syslog server. Currently, R1 shows 'Clock is unsynchronized, stratum 16'. Identify and fix the NTP issue, then apply the syslog configuration.

Accepted Answer

Configure 'ntp source Loopback0' and 'logging trap informational'.. The NTP client was configured but the source interface was not specified, causing the router to use a default source that may not be reachable. Additionally, the syslog trap level was set to 'warnings' (severity 4), which filters out informational (severity 6) messages. To fix: configure 'ntp source Loopback0' to use a consistent source IP, and change 'logging trap informational' to allow all messages severity 6 and above.

Answer

Configure 'ntp server 203.0.113.10 source Loopback0' and 'logging trap warnings'.

Answer

Configure 'ntp source Loopback0' and 'logging trap debugging'.

Answer

Configure 'ntp source Loopback0' and 'logging host 198.51.100.20' without changing the trap level.

Question 15

You are connected to R1. Configure R1 as a DHCP server for the 192.168.100.0/24 subnet, reserving the first 10 addresses and the address 192.168.100.254 for static assignments, with default gateway 192.168.100.1 and DNS server 8.8.8.8. Then, on the same router, enable DHCP relay for the 10.1.1.0/24 subnet by configuring the helper address pointing to the DHCP server at 192.168.100.1. Finally, verify that the DHCP pool is correctly configured and that the helper address is set.

Accepted Answer

The default-router is incorrectly set to 192.168.100.254 instead of 192.168.100.1, and the ip helper-address on G0/1 points to 192.168.100.254 instead of 192.168.100.1.. The configuration has two critical errors. First, the default-router in the DHCP pool is incorrectly set to 192.168.100.254, which is an excluded address meant for static assignment, not the actual gateway (192.168.100.1). Second, the ip helper-address on G0/1 points to 192.168.100.254 (the wrong address) instead of the DHCP server's own interface IP 192.168.100.1. To fix, change the default-router to 192.168.100.1 and update the helper-address to 192.168.100.1.

Answer

The default-router is correctly set to 192.168.100.1, but the ip helper-address on G0/1 points to 192.168.100.254 instead of 192.168.100.1.

Answer

The default-router is incorrectly set to 192.168.100.254 instead of 192.168.100.1, but the ip helper-address on G0/1 correctly points to 192.168.100.1.

Answer

Both the default-router and the ip helper-address are correctly configured as 192.168.100.1.

Question 16

You are connected to R1 via the console. R1 should synchronize its clock with the NTP server 192.0.2.10 using its loopback0 interface (IP 10.0.0.1) as the source. Additionally, syslog messages of severity 'notification' (level 5) and above must be sent to the syslog server at 198.51.100.20. Currently, R1 shows NTP stratum 16 (unsynchronized) and syslog messages are not being forwarded. Identify and resolve the issues.

Accepted Answer

Add 'ntp server 192.0.2.10' and change 'logging trap informational' to 'logging trap notifications'.. The NTP is unsynchronized because the 'ntp server' command is missing; only 'ntp source' is configured. Add 'ntp server 192.0.2.10' to point to the NTP server. The syslog trap level is set to 'informational' (level 6), which is too low—messages of level 5 (notification) are not sent because the trap level must be equal to or higher severity than the messages to be forwarded. Change the trap level to 'notifications' (level 5) to ensure level 0-5 messages are forwarded.

Answer

Add 'ntp server 192.0.2.10' and change 'logging trap notifications' to 'logging trap informational'.

Answer

Add 'ntp server 192.0.2.10' and change 'logging trap notifications' to 'logging trap debugging'.

Answer

Add 'ntp server 192.0.2.10' and change 'logging trap informational' to 'logging trap emergencies'.

Question 17

You are connected to R1 (a router acting as DHCP server) via the console. Configure R1 to provide DHCP addresses for VLAN 10 (192.168.10.0/24) on the switch SW1, which is connected via R1's G0/0. Exclude the first 10 addresses (192.168.10.1-10) and the last address (192.168.10.254). Set the default gateway to 192.168.10.1 and DNS server to 203.0.113.10. On SW1, enable DHCP snooping globally and for VLAN 10, configure G0/1 as trusted toward R1, and ensure the ip helper-address on the switch's VLAN 10 SVI points to R1's G0/0 IP. The current config has a wrong helper-address and an oversized excluded range; identify and fix all issues.

Accepted Answer

On R1: ip dhcp excluded-address 192.168.10.1 192.168.10.10 and ip dhcp excluded-address 192.168.10.254; ip dhcp pool VLAN10: network 192.168.10.0 255.255.255.0, default-router 192.168.10.1, dns-server 203.0.113.10. On SW1: ip dhcp snooping, ip dhcp snooping vlan 10, interface G0/1: ip dhcp snooping trust, interface Vlan10: ip helper-address 10.0.0.1.. The DHCP server R1 had an excluded range that covered the entire subnet (192.168.10.1 through 192.168.10.254), preventing any addresses from being assigned. This was corrected by first removing that oversized exclusion, then setting the excluded range to 192.168.10.1 192.168.10.10 and adding 192.168.10.254 as a separate excluded address. On SW1, the ip helper-address pointed to 192.168.20.1 (wrong), which should be R1's G0/0 IP 10.0.0.1. Also, DHCP snooping was enabled globally and for VLAN 10, but G0/1 (link to R1) was not trusted; it was set to trusted. These changes allow DHCP requests from VLAN 10 to be relayed to R1 and trusted from the correct interface. Option A is technically incomplete because it fails to include the removal of the original oversized exclusion.

Answer

On R1: ip dhcp excluded-address 192.168.10.1 192.168.10.10; ip dhcp pool VLAN10: network 192.168.10.0 255.255.255.0, default-router 192.168.10.1, dns-server 203.0.113.10. On SW1: ip dhcp snooping, ip dhcp snooping vlan 10, interface G0/1: ip dhcp snooping trust, interface Vlan10: ip helper-address 192.168.10.1.

Answer

On R1: ip dhcp excluded-address 192.168.10.1 192.168.10.10; ip dhcp pool VLAN10: network 192.168.10.0 255.255.255.0, default-router 192.168.10.1, dns-server 203.0.113.10. On SW1: ip dhcp snooping, ip dhcp snooping vlan 10, interface Vlan10: ip helper-address 10.0.0.1.

Answer

On R1: ip dhcp excluded-address 192.168.10.1 192.168.10.254; ip dhcp pool VLAN10: network 192.168.10.0 255.255.255.0, default-router 192.168.10.1, dns-server 203.0.113.10. On SW1: ip dhcp snooping, ip dhcp snooping vlan 10, interface G0/1: ip dhcp snooping trust, interface Vlan10: ip helper-address 10.0.0.1.

Question 18

You are connected to R1. Configure NTP client so that R1 synchronizes with the NTP server at 198.51.100.10, using its Loopback0 (10.0.0.1/32) as the source interface. Also configure syslog to send messages of severity 5 (notifications) and above to 192.0.2.20. The current configuration shows a misconfigured NTP server address and an incorrect logging trap level. Verify with 'show ntp status' (stratum should not be 16) and 'show logging'.

Accepted Answer

ntp server 198.51.100.10 source Loopback0
logging trap notifications. The misconfigured NTP server address (203.0.113.5) and the debug-level logging trap (7) must be corrected to meet requirements. The correct commands are 'ntp server 198.51.100.10 source Loopback0' to use the specified server and Loopback0 as source, and 'logging trap notifications' (severity 5) to send only notifications and more severe messages. Option B is wrong because 'logging trap 4' sets the trap level to warning, which would not forward notifications. Option C misses the source interface, and Option D uses the wrong NTP server and an overly verbose trap level.

Answer

ntp server 198.51.100.10 source Loopback0
logging trap 4

Answer

ntp server 198.51.100.10
logging trap notifications

Answer

ntp server 203.0.113.5 source Loopback0
logging trap 7

Question 19

You 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.

Accepted Answer

On R1, change the excluded-address range to 192.168.20.1 192.168.20.1; on SW1, configure ip helper-address 10.0.0.1 under interface Vlan20; enable DHCP snooping globally and on VLAN 20, and configure the uplink to R1 as trusted.. The DHCP server had an excluded-address range covering the entire subnet (192.168.20.0–255), which prevented any IP from being assigned. Fix: change the excluded range to only include the gateway (192.168.20.1) and optionally other reserved addresses. The helper-address on SW1 pointed to 192.0.2.99 (nonexistent) instead of the DHCP server at 10.0.0.1; correct it. DHCP snooping was disabled; enable it globally and on VLAN 20, then configure the uplink to R1 (port connecting to R1) as trusted and the port connecting the rogue server (Fa0/3) as untrusted (or simply leave it untrusted by default, but the rogue server will be blocked).

Answer

On R1, remove the excluded-address range entirely; on SW1, configure ip helper-address 192.168.20.1 under interface Vlan20; enable DHCP snooping globally and on VLAN 20, and configure the uplink to R1 as trusted.

Answer

On R1, change the excluded-address range to 192.168.20.1 192.168.20.254; on SW1, configure ip helper-address 192.0.2.99 under interface Vlan20; enable DHCP snooping globally and on VLAN 20, and configure the uplink to R1 as trusted.

Answer

On R1, change the excluded-address range to 192.168.20.1 192.168.20.1; on SW1, configure ip helper-address 10.0.0.1 under interface Vlan20; enable DHCP snooping globally and on VLAN 20, but do not configure any trusted ports.

Question 20

You are connected to R1 via console. R1 is a Cisco ISR 4321 running IOS-XE 17.3. The initial configuration on R1 already includes the SNMPv2c community string 'CourseivaRO' with read-only access and a corresponding SNMPv2c trap host for 192.0.2.100 (these are already in place and do not need to be reconfigured). Your task is to add the following additional configurations: (a) [already configured] (b) Create an SNMPv3 user 'monitor' with SHA authentication and AES 128-bit encryption, using authentication password 'AuthPass123' and privacy password 'PrivPass456'; (c) Configure SNMP traps (linkUp, linkDown, authenticationFailure) to be sent to the NMS server at 192.0.2.100 using SNMPv3 with only authentication (no privacy). (d) Enable NetFlow on GigabitEthernet0/0/0, with flow export to collector 203.0.113.50 using UDP port 2055, NetFlow version 9, and set the source interface to Loopback0 (IP 10.0.0.1/32). Finally, verify your configuration with show snmp and show ip cache flow.

Accepted Answer

snmp-server user monitor CourseivaRO v3 auth sha AuthPass123 priv aes 128 PrivPass456
snmp-server host 192.0.2.100 version 3 auth monitor
interface GigabitEthernet0/0/0
 ip flow ingress
ip flow-export destination 203.0.113.50 2055
ip flow-export source Loopback0
ip flow-export version 9. Option A is correct because it uses the correct SNMPv3 user creation with SHA and AES 128, and the trap host command specifies 'auth' (authentication only) as required by the updated stem. Option B is wrong because it uses MD5/DES and egress flow, and version 5. Option C is wrong because it uses 'priv' for traps, which would include encryption – the stem requires only authentication. Option D is wrong because it uses version 5 for NetFlow and B also uses incorrect auth/priv algorithms.

Answer

snmp-server user monitor CourseivaRO v3 auth md5 AuthPass123 priv des56 PrivPass456
snmp-server host 192.0.2.100 version 3 priv monitor
interface GigabitEthernet0/0/0
 ip flow egress
ip flow-export destination 203.0.113.50 2055
ip flow-export source Loopback0
ip flow-export version 5

Answer

snmp-server user monitor CourseivaRO v3 auth sha AuthPass123 priv aes 128 PrivPass456
snmp-server host 192.0.2.100 version 3 priv monitor
interface GigabitEthernet0/0/0
 ip flow ingress
ip flow-export destination 203.0.113.50 2055
ip flow-export source Loopback0
ip flow-export version 9

Answer

snmp-server user monitor CourseivaRO v3 auth sha AuthPass123 priv aes 128 PrivPass456
snmp-server host 192.0.2.100 version 3 auth monitor
interface GigabitEthernet0/0/0
 ip flow ingress
ip flow-export destination 203.0.113.50 2055
ip flow-export source Loopback0
ip flow-export version 5

CCNA Mock Exam 82 — 25 Questions

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CCNA Mock Exam 82 — 25 Questions

Exhibit