300-410 Practice Test 42 — 15 Questions

Question 1

A network engineer runs the following command on Router R9:

R9# show logging | include %DMVPN-5-ADJCHG

*Mar  1 00:01:05.123: %DMVPN-5-ADJCHG: NHRP: Peer 10.0.0.1 on Tunnel0 is UP
*Mar  1 00:02:10.456: %DMVPN-5-ADJCHG: NHRP: Peer 10.0.0.1 on Tunnel0 is DOWN
*Mar  1 00:03:15.789: %DMVPN-5-ADJCHG: NHRP: Peer 10.0.0.1 on Tunnel0 is UP
*Mar  1 00:04:20.012: %DMVPN-5-ADJCHG: NHRP: Peer 10.0.0.1 on Tunnel0 is DOWN

Based on this output, what is the most likely problem?

Accepted Answer

The DMVPN tunnel is flapping due to an unstable IPsec SA.. The output shows NHRP peer flapping on Tunnel0, indicating that the DMVPN tunnel is unstable. This is often due to a flaking physical interface, IPsec SA expiration, or routing issues. The peer 10.0.0.1 is going up and down repeatedly.

Answer

The NHRP hold time is set too high.

Answer

The router has a mismatched DMVPN phase configuration.

Answer

The tunnel interface is administratively down.

Question 2

An engineer enables uRPF (unicast Reverse Path Forwarding) in strict mode on an interface connected to a DMVPN spoke. The spoke has multiple tunnels and receives traffic from the hub with a source IP that is not the best reverse path. Unexpectedly, the spoke drops all traffic from the hub, even though the hub is reachable via the tunnel. Which is the most likely explanation?

Accepted Answer

uRPF strict mode requires the reverse path to be via the same interface; asymmetric routing causes drops.. uRPF strict mode checks that the source IP of incoming packets has a route back to the source via the same interface. In DMVPN, the hub's source IP may be reachable via a different interface (e.g., physical interface) than the tunnel interface where the packet arrives. This asymmetric routing causes uRPF strict mode to drop the packets. The solution is to use loose mode or allow-default.

Answer

The hub's IP address is not in the routing table, so uRPF drops the packet.

Answer

uRPF must be configured with the `allow-default` option to accept packets with default route.

Answer

uRPF is not supported on tunnel interfaces; it must be applied on the physical interface.

Question 3

Two routers are configured with EIGRP and have a neighbor relationship. One router has a route to 192.168.1.0/24 with metric 100. The other router has a route to the same prefix with metric 200. An engineer configures an offset-list on the first router to increase the metric of 192.168.1.0/24 by 50, expecting the second router to prefer its own route. Unexpectedly, the second router still prefers the first router's route after the offset. Which is the most likely explanation?

Accepted Answer

The offset-list increased the metric from 100 to 150, which is still lower than the second router's metric of 200, so the second router still prefers the first router's route.. The offset-list affects the metric of the route as advertised to the neighbor. However, if the offset-list is applied inbound on the second router, it increases the metric of the received route, making it less preferred. But if the offset-list is applied outbound on the first router, it increases the metric of the route sent to the second router. The second router then compares the received metric (150) with its own metric (200) and still prefers the lower metric (150). The engineer likely applied the offset-list outbound on the first router, but the increase was insufficient to make the second router's route better.

Answer

The offset-list must be applied inbound on the second router to increase the metric of the received route.

Answer

The offset-list command only affects feasible distance, not advertised distance, so the second router ignores it.

Answer

The second router has a higher administrative distance for the route, so it always prefers the first router's route.

Question 4

Examine the following partial router configuration:

logging buffered 16384
logging console warnings
logging monitor notifications
logging trap debugging
logging source-interface Loopback0
logging 192.168.1.100

What is the effect of this configuration?

Accepted Answer

Syslog messages of severity 0 through 7 are sent to the server 192.168.1.100.. This configuration sets up logging with different severity levels for different destinations. The 'logging trap debugging' sends all messages (severity 0-7) to the syslog server at 192.168.1.100, while console gets only warnings (severity 4) and monitor gets notifications (severity 5). The buffer is set to 16384 bytes.

Answer

Only syslog messages of severity 0 through 4 are sent to the server 192.168.1.100.

Answer

The syslog server receives messages with the IP address of the outgoing interface as the source.

Answer

The logging buffer stores up to 16384 syslog messages.

Question 5

Given the following partial configuration on a Cisco IOS-XE router:

logging host 10.1.1.1 transport tcp port 514
logging source-interface GigabitEthernet0/1
logging on

What is missing or incorrect in this configuration?

Accepted Answer

The syslog server must support TCP syslog, which is not defined in RFC 3164.. By default, syslog uses UDP port 514. When using TCP transport, the syslog server must be configured to accept TCP connections, and this is not a common configuration. The configuration itself is syntactically correct, but the question tests knowledge that TCP transport for syslog is non-standard and may not work with typical syslog servers.

Answer

The configuration is correct; no changes are needed.

Answer

The 'logging on' command is redundant because logging is enabled by default.

Answer

The port number should be 5140 for TCP syslog.

Question 6

A network engineer is troubleshooting an OSPFv2 adjacency issue between two directly connected routers, R1 and R2, both running IOS-XE. The link is a point-to-point Ethernet link. The engineer issues 'show ip ospf neighbor' on R1 and sees no neighbors. 'show ip ospf interface GigabitEthernet0/0' on R1 shows 'Network Type BROADCAST', but the link is actually a point-to-point link. Both routers have 'ip ospf 1 area 0' configured on the interface. What is the most likely cause of the adjacency not forming?

Accepted Answer

The routers have duplicate OSPF router IDs.. The default OSPF network type on Ethernet interfaces is BROADCAST, which requires a DR/BDR election and uses multicast 224.0.0.5 and 224.0.0.6. On a point-to-point link, if both routers do not agree on the network type, they may not form an adjacency because the hello packets are sent differently. However, since both are BROADCAST, they should form an adjacency. The real issue is likely a mismatch in OSPF network type if one side is manually set to POINT-TO-POINT, but here both are BROADCAST. A more common cause is that the interface is administratively down or there is a Layer 1 issue, but the stem indicates the interface is up. Another common cause is that the router IDs are not configured, leading to OSPF not starting. The most likely cause in this scenario is that the routers have duplicate router IDs, which prevents adjacency formation. The stem does not mention router IDs, so the best answer is that the engineer should check for duplicate router IDs.

Answer

The OSPF network type mismatch between the two routers (one is BROADCAST, the other is POINT-TO-POINT).

Answer

The interface is configured with 'ip ospf passive-interface'.

Answer

The OSPF process is not enabled globally; 'router ospf 1' is missing.

Question 7

Refer to the following partial configuration:

logging console informational
logging monitor debugging
logging trap errors
logging buffered 4096

Which statement is true about the logging levels?

Accepted Answer

The console receives messages of severity 0 through 6.. Logging levels: emergencies (0), alerts (1), critical (2), errors (3), warnings (4), notifications (5), informational (6), debugging (7). The trap level 'errors' means only messages severity 0-3 are sent to syslog servers. Console 'informational' means 0-6. Monitor 'debugging' means 0-7. Buffer defaults to debugging if not specified, but here it is set to 4096 bytes without a level, so it defaults to debugging.

Answer

The monitor receives messages of severity 0 through 6.

Answer

The syslog server receives messages of severity 0 through 7.

Answer

The buffer stores messages of severity 0 through 6.

Question 8

Which TWO statements about syslog message severity levels are true? (Choose TWO.)

Accepted Answer

Severity level 0 (emergencies) is the most critical and indicates system instability.. Syslog severity levels range from 0 (emergencies) to 7 (debugging). Level 0 is the most critical, and level 7 is the least critical. Level 5 is 'notifications', not 'warnings'; warnings are level 4. Level 6 is 'informational'. Level 3 is 'errors'.

Answer

Severity level 5 (warnings) is less severe than level 4 (notifications).

Answer

Severity level 6 (informational) is used for system error messages.

Answer

Severity level 3 (errors) is more critical than level 2 (critical).

Question 9

A network engineer is troubleshooting OSPFv3 on a dual-stack network. Routers R1 and R2 are connected via a serial link. Both routers have OSPFv3 configured for IPv6. The engineer runs 'show ipv6 ospf neighbor' on R1 and sees R2 as FULL/DR. However, R1 cannot ping the IPv6 address of R2's loopback interface. 'show ipv6 route ospf' on R1 does not show any OSPF routes. What is the most likely cause?

Accepted Answer

The interface on R1 does not have an IPv6 address configured.. In OSPFv3, the network type on serial interfaces defaults to POINT-TO-POINT, but if the interface is configured as BROADCAST (e.g., using 'ipv6 ospf network broadcast'), a DR/BDR election occurs. However, the adjacency is FULL, so the issue is not adjacency. The lack of OSPF routes in the routing table suggests that the routes are not being installed. One common reason is that OSPFv3 requires an IPv6 address on the interface, but the router may have an IPv4-only configuration or the interface may not have an IPv6 address. Another possibility is that the OSPFv3 process is not redistributing connected routes. The most likely cause is that the interface does not have an IPv6 address configured, which is required for OSPFv3 to advertise prefixes.

Answer

The OSPFv3 process has 'no ipv6 unicast-routing' enabled globally.

Answer

The interface on R2 is configured as passive under OSPFv3.

Answer

The OSPFv3 process is configured with 'default-information originate always' but no default route exists.

Question 10

Consider the configuration snippet:

logging 192.168.1.10 vrf Mgmt-intf
logging source-interface Vlan1
logging trap 6

What is the effect of the 'logging trap 6' command?

Accepted Answer

Messages of severity 0 through 6 are sent to the syslog server.. The 'logging trap' command accepts either a severity level name or number. Level 6 corresponds to 'informational'. This means messages with severity 0-6 are sent to the syslog server.

Answer

Only messages of severity 6 are sent to the syslog server.

Answer

Messages of severity 6 through 7 are sent to the syslog server.

Answer

The number 6 is invalid; only named levels are accepted.

Question 11

A network engineer is troubleshooting OSPFv2 route redistribution. R1 is an ASBR redistributing static routes into OSPF. R2, an internal router, receives the redistributed routes but they appear as O E2 routes. However, R1 also has a directly connected network 10.1.1.0/24 that is not being advertised as an OSPF route. 'show ip ospf database external' on R2 shows the redistributed static routes but not the connected network. What is the most likely cause?

Accepted Answer

The ASBR is missing the 'redistribute connected' command under the OSPF process.. By default, OSPF does not redistribute connected routes unless explicitly configured. The ASBR must use the 'redistribute connected' command under the OSPF process to advertise directly connected networks. The static routes are being redistributed because they are matched by the 'redistribute static' command, but the connected network is not part of the static route set unless it is also a static route. The engineer likely forgot to add 'redistribute connected' or use the 'subnets' keyword.

Answer

The connected network is not included in the redistribution because the engineer used 'redistribute static' without the 'subnets' keyword.

Answer

The connected network is not being advertised because it is not part of the OSPF process; the engineer must configure 'network 10.1.1.0 0.0.0.255 area 0' under router ospf.

Answer

The connected network is a loopback interface, and OSPF does not advertise loopback networks by default.

Question 12

Examine the following configuration:

logging host 10.1.1.1
logging host 10.1.1.2
logging host 10.1.1.3
logging origin-id hostname
logging facility local7

What is the purpose of the 'logging origin-id hostname' command?

Accepted Answer

It causes the syslog messages to include the router's hostname as the origin, overriding the default IP address.. The 'logging origin-id' command sets the origin identifier in syslog messages. When set to 'hostname', the router's hostname is used as the origin ID instead of the default (which is the IP address of the source interface). This helps identify the source of messages in a multi-device environment.

Answer

It sets the syslog message format to include the hostname in the timestamp field.

Answer

It configures the router to send syslog messages only when the hostname changes.

Answer

It is used to authenticate syslog messages using the hostname as a key.

Question 13

A network engineer is troubleshooting an OSPFv2 adjacency issue between two routers across a Frame Relay network. R1 and R2 are connected via a point-to-point subinterface. The engineer configures 'ip ospf network point-to-point' on both subinterfaces. However, the adjacency does not form. 'show ip ospf interface' on R1 shows the interface is up and OSPF is enabled, but no neighbors are seen. What is the most likely cause?

Accepted Answer

The Frame Relay map is missing or the DLCI is not assigned to the subinterface.. On Frame Relay point-to-point subinterfaces, the OSPF network type should be point-to-point, but the adjacency may still fail if the Layer 2 mapping is incorrect. The subinterface must be mapped to the correct DLCI. If the 'frame-relay interface-dlci' command is missing or misconfigured, the router cannot send packets to the neighbor, even though OSPF is enabled. The engineer should verify the DLCI mapping.

Answer

The OSPF network type is set to broadcast, causing a DR/BDR election that fails on a point-to-point subinterface.

Answer

The subinterface is not configured with an IP address.

Answer

The OSPF hello and dead timers are mismatched between R1 and R2.

Question 14

A network engineer is troubleshooting an OSPFv3 issue where a router R1 is not learning routes from a neighbor R2. The adjacency is FULL, but 'show ipv6 route ospf' on R1 shows only a default route. R2 is an ASBR redistributing connected routes into OSPFv3. 'show ipv6 ospf database external' on R1 shows the external routes, but they are not installed in the routing table. What is the most likely cause?

Accepted Answer

The router R1 has a distribute-list in the OSPFv3 process that filters out the external routes.. In OSPFv3, external routes are not installed if the router has a route to the forwarding address that is not reachable. However, the more common cause is that the OSPFv3 process on R1 has 'no ipv6 unicast-routing' or the router is missing a default route to reach the external destinations. Another possibility is that the external routes have a metric that is too high or the route is suppressed by a filter. The most likely cause is that the router has a route map or distribute list that is filtering the external routes from being installed.

Answer

The external routes have a metric of 16777214, which is considered infinite.

Answer

The router R1 does not have IPv6 unicast routing enabled.

Answer

The external routes are type 5 LSAs but the router is in a totally stubby area.

Question 15

A network engineer is troubleshooting an OSPFv2 route flapping issue. The router R1 is learning a route to 192.168.1.0/24 via two different paths: one through R2 and one through R3. The route is flapping between the two paths every few seconds. 'show ip ospf interface' shows that both interfaces are stable. What is the most likely cause?

Accepted Answer

The routers R2 and R3 have the same OSPF router ID.. Route flapping can be caused by a number of issues, but if the interfaces are stable, the problem is likely due to a routing loop or a metric issue. One common cause is that the routers are using the same router ID, causing OSPF to see the same route from two different neighbors as equal-cost paths, but the route may be flapping due to a change in the metric. Another cause is that the link between R1 and R2 is flapping at Layer 1, but the stem says the interfaces are stable. The most likely cause is that the routers have duplicate router IDs, which can cause OSPF to treat the same route as two different routes and cause instability.

Answer

The route is being redistributed by both R2 and R3 with different metrics.

Answer

The OSPF network type on the interfaces is set to broadcast, causing DR/BDR instability.

Answer

The link between R1 and R2 has a high error rate causing intermittent packet loss.