300-410 Practice Test 39 — 15 Questions

Question 1

A network engineer runs the following command to troubleshoot an EIGRP issue:

R1# show ip eigrp neighbors detail

IP-EIGRP neighbors for process 100
H   Address                 Interface       Hold Uptime   SRTT   RTO  Q  Seq
                                           (sec)         (ms)       Cnt Num
0   10.1.2.2                Gi0/0            13 00:12:34   12   200  0  145
   Version 12.4/1.2, Retrans: 0, Retries: 0, Prefixes: 5
   Topology-ids from peer - 0
   Stub Peer Advertising (CONNECTED STATIC) Routes
   Suppressing queries

What does this output indicate?

Accepted Answer

The neighbor is a stub router that only advertises connected and static routes, and it does not participate in query propagation.. The neighbor 10.1.2.2 is a stub router advertising only connected and static routes. The neighbor is suppressing queries, meaning it will not forward queries from R1 to other routers, which can affect route convergence.

Answer

The neighbor is a normal EIGRP peer that forwards all routes and queries.

Answer

The neighbor is not forming an adjacency due to a version mismatch.

Answer

The neighbor is using a different autonomous system number.

Question 2

What is the default behavior of EIGRP auto-summary in IOS-XE 15.x and later?

Accepted Answer

Auto-summary is disabled by default. Starting from IOS 15.0(1)M, EIGRP auto-summary is disabled by default. This prevents automatic summarization at classful boundaries, which can cause routing issues in discontiguous networks.

Answer

Auto-summary is enabled by default

Answer

Auto-summary is enabled only for connected routes

Answer

Auto-summary is disabled only for point-to-point links

Question 3

A network engineer runs the following command to troubleshoot an EIGRP issue:

R1# debug eigrp packets update

*Mar  1 00:10:15.456: EIGRP: received packet with opcode = 2 (Update) on GigabitEthernet0/0, src 10.1.2.2 dst 10.1.2.1
*Mar  1 00:10:15.456:   EIGRP: Update contains 5 routes, version 145, seq 10
*Mar  1 00:10:15.456:   EIGRP: Update update/interval, 10.1.1.0/24 metric 131072
*Mar  1 00:10:15.456:   EIGRP: Update update/interval, 10.2.2.0/24 metric 131072
*Mar  1 00:10:15.456:   EIGRP: Update update/interval, 10.3.3.0/24 metric 131072
*Mar  1 00:10:15.456:   EIGRP: Update update/interval, 10.4.4.0/24 metric 131072
*Mar  1 00:10:15.456:   EIGRP: Update update/interval, 10.5.5.0/24 metric 131072

What does this output indicate?

Accepted Answer

The neighbor is sending a periodic update with five routes, which is normal EIGRP behavior.. The debug shows an EIGRP Update packet received from 10.1.2.2 containing five routes. This is a normal update, likely sent as a periodic or triggered update. The 'update/interval' indicates the update is being sent due to the periodic update timer.

Answer

The neighbor is sending a partial update with five routes, which is typical for a triggered update after a topology change.

Answer

The neighbor is sending a full update, which occurs during initial neighbor formation or after a major change.

Answer

The neighbor is sending an update with incorrect metrics, causing routing issues.

Question 4

Which EIGRP loop prevention mechanism prevents a router from installing a route that was originally learned from itself?

Accepted Answer

Feasibility condition. EIGRP uses the Feasibility Condition (FC) to ensure loop-free paths. A route is feasible if the reported distance from the neighbor is less than the current feasible distance. This prevents a router from accepting a route that could loop back.

Answer

Split horizon

Answer

Route poisoning

Answer

Hold-down timer

Question 5

An engineer is troubleshooting why syslog messages from a router are not being received by the syslog server at 192.168.1.10. The router configuration includes 'logging host 192.168.1.10' and 'logging trap 6'. The engineer runs 'debug ip packet' and sees packets destined for 192.168.1.10 being sent but no response. What should the engineer check first?

Accepted Answer

Verify that the syslog server is running and listening on UDP port 514.. Syslog uses UDP, which is connectionless; the server does not send acknowledgments. The debug showing packets being sent indicates the router is transmitting, but the server may not be listening on UDP 514, or a firewall may be blocking the traffic. Checking the server's syslog service status and firewall rules is the logical first step.

Answer

Change the logging trap level to 7 (debugging) to ensure all messages are sent.

Answer

Add the 'logging source-interface' command to use a loopback interface.

Answer

Configure 'logging on' if it is not already enabled.

Question 6

A network engineer runs the following command to troubleshoot an EIGRP issue:

R1# show ip eigrp interfaces detail

Interface GigabitEthernet0/0
  EIGRP interface state: Enabled, Up
  Hello interval: 5 sec, Hold time: 15 sec
  Split horizon: Enabled
  Next multicast: 0.0.0.0, Next update: 0.0.0.0
  Bandwidth: 10000 Kbit, Delay: 100 us
  Reliability: 255/255, Load: 1/255, MTU: 1500
  Packets sent: 100, received: 95
  Authentication: MD5, key chain: EIGRP-KEY
  Passive interface: No

What does this output indicate?

Accepted Answer

EIGRP is using MD5 authentication with key chain EIGRP-KEY, and the interface is actively sending and receiving EIGRP packets.. The output shows that EIGRP is enabled on GigabitEthernet0/0 with MD5 authentication using key chain EIGRP-KEY. The interface is not passive, and split horizon is enabled. The hello and hold timers are default.

Answer

EIGRP is configured as a passive interface, so no hellos are sent.

Answer

Split horizon is disabled, allowing route advertisement back to the source.

Answer

The interface is using plain-text authentication.

Question 7

What is the default EIGRP authentication mode when authentication is configured?

Accepted Answer

MD5. EIGRP supports MD5 authentication by default. When 'ip authentication mode eigrp' is configured, the default mode is MD5. SHA-256 requires additional configuration.

Answer

SHA-256

Answer

Plain text

Answer

No authentication by default

Question 8

A network engineer is troubleshooting a router that is generating excessive syslog messages, filling up the local logging buffer and causing performance issues. The engineer wants to reduce the volume of messages sent to the remote syslog server while still capturing critical alerts locally. The current configuration includes 'logging buffered 4096 debugging' and 'logging host 10.1.1.100'. What is the best approach?

Accepted Answer

Configure 'logging trap errors' under the logging host configuration to limit remote messages to severity 3 and above.. To reduce remote syslog volume without affecting local logging, the engineer should set a higher severity threshold for the remote server using 'logging trap' (e.g., 'logging trap 3' for errors only). The local buffer can remain at debugging level for detailed troubleshooting. This separates the logging levels.

Answer

Change 'logging buffered 4096 debugging' to 'logging buffered 4096 errors' to reduce local messages.

Answer

Remove the 'logging buffered' command to stop all local logging.

Answer

Add 'logging rate-limit 10' to limit the number of messages per second.

Question 9

A network engineer runs the following command to troubleshoot an EIGRP issue:

R1# show ip eigrp traffic

IP-EIGRP Traffic Statistics for process 100
  Hellos sent/received: 500/495
  Updates sent/received: 10/8
  Queries sent/received: 2/1
  Replies sent/received: 1/2
  Acks sent/received: 8/10
  Input queue high water mark: 2, Input queue depth: 0
  Total packets sent: 521, received: 516

What does this output indicate?

Accepted Answer

The EIGRP process is functioning normally with no signs of congestion or issues.. The output shows EIGRP traffic statistics. The number of queries and replies is low, indicating a stable network. The input queue depth is 0, meaning no packets are queued. This is normal operation.

Answer

The network is experiencing a high number of queries, indicating instability.

Answer

There is a problem with packet loss because more hellos were sent than received.

Answer

The router is not receiving acknowledgments for its updates.

Question 10

What is the maximum hop count for an EIGRP route?

Accepted Answer

224. EIGRP uses a maximum hop count of 224 (or 255 in some implementations) to prevent routing loops. However, the default metric calculation does not include hop count; it is only used as a tie-breaker or limit.

Answer

15

Answer

255

Answer

Unlimited

Question 11

A router is configured with 'logging host 10.1.1.100' and 'logging trap informational'. The engineer notices that syslog messages with severity 5 (notice) are being sent, but messages with severity 6 (informational) are not. What is the most likely cause?

Accepted Answer

The 'logging trap' command is set to 5 (notice) rather than 6 (informational).. The 'logging trap informational' command sets the severity threshold to 6, meaning messages of severity 0-6 are sent. However, if the engineer sees that severity 5 messages are sent but severity 6 are not, the issue is likely that the specific informational messages are not being generated by the router, or they are being filtered by a different mechanism such as 'logging filter' or 'exception' settings. But the most common cause is that the 'logging trap' level is actually set to 5 (notice) instead of 6. A misconfiguration or misunderstanding of the command is typical.

Answer

The syslog server is dropping severity 6 messages due to its own configuration.

Answer

The 'logging console' command is overriding the remote logging level.

Answer

The router's clock is not synchronized, causing timestamp issues.

Question 12

A network engineer runs the following command to troubleshoot an EIGRP issue:

R1# debug eigrp fsm

*Mar  1 00:20:45.678: EIGRP: 10.1.1.0/24 - do advertising, metric 131072
*Mar  1 00:20:45.678: EIGRP: 10.1.1.0/24 - route installed in table
*Mar  1 00:20:45.678: EIGRP: 10.1.1.0/24 - metric change from 131072 to 131328
*Mar  1 00:20:45.678: EIGRP: 10.1.1.0/24 - find FS, metric 131328, RD 130816
*Mar  1 00:20:45.678: EIGRP: 10.1.1.0/24 - found FS via 10.1.3.3, metric 131328
*Mar  1 00:20:45.678: EIGRP: 10.1.1.0/24 - new successor is 10.1.3.3

What does this output indicate?

Accepted Answer

EIGRP is performing a Diffusing Update Algorithm (DUAL) recomputation due to a metric increase, but a feasible successor is available, so no query is needed.. The debug shows the EIGRP Finite State Machine (FSM) processing a route change. The metric for 10.1.1.0/24 increased from 131072 to 131328, and the router found a feasible successor (10.1.3.3) with a metric of 131328, which becomes the new successor. This is a normal convergence event.

Answer

The route 10.1.1.0/24 has become unreachable, and EIGRP is querying neighbors.

Answer

The route is being removed from the topology table because the metric changed.

Answer

EIGRP is sending a query to all neighbors because no feasible successor exists.

Question 13

Which of the following is the default EIGRP network type on a Frame Relay point-to-point subinterface?

Accepted Answer

Point-to-point. EIGRP automatically detects the interface type. For point-to-point subinterfaces, it defaults to point-to-point network type, which uses 5-second hellos and does not require a DR/BDR.

Answer

NBMA

Answer

Broadcast

Answer

Point-to-multipoint

Question 14

An engineer is troubleshooting a router that is not sending syslog messages to the remote server at 192.168.1.10. The configuration includes 'logging host 192.168.1.10' and 'logging trap 7'. The router can ping 192.168.1.10. The engineer runs 'show logging' and sees 'Syslog logging: enabled (0 messages dropped, 0 messages rate-limited, 0 flushes, 0 overruns)'. What is the most likely cause?

Accepted Answer

The 'logging source-interface' is configured to an interface that is administratively down.. The 'show logging' output shows that syslog is enabled but no messages are being sent. A common reason is that the 'logging source-interface' is set to an interface that is down or not reachable, causing the router to use an incorrect source IP that the server may filter or that routing may not support. Alternatively, the server may be configured to accept messages only from specific source IPs.

Answer

The 'logging on' command is missing from the configuration.

Answer

The syslog server is using TCP, but the router is configured for UDP.

Answer

The logging buffer is full, preventing new messages from being generated.

Question 15

A network engineer runs the following command to troubleshoot an EIGRP issue:

R1# show ip eigrp topology 10.1.1.0/24 detail

IP-EIGRP (AS 100): Topology entry for 10.1.1.0/24
  State: Passive, Query origin flag: 1, 1 Successor(s), FD is 131072
  Routing Descriptor Blocks:
  10.1.2.2 (GigabitEthernet0/0), from 10.1.2.2, Send flag: 0x0
      Composite metric: (131072/130816), Route is Internal
      Vector metric:
        Minimum bandwidth is 10000 Kbit
        Total delay is 100 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 1
      Originating router: 10.1.2.2
      External data: Not advertised
      Protocol: EIGRP
      Route tag: 0
      Extended community: None

What does this output indicate?

Accepted Answer

The route is learned from a single neighbor and is in a stable state.. The output shows detailed information about the EIGRP topology entry for 10.1.1.0/24. The route is internal, with a single successor via 10.1.2.2. The FD is 131072, and the RD is 130816. The route is in Passive state.

Answer

The route is an external EIGRP route redistributed from another protocol.

Answer

The route has multiple successors and is load-balanced.

Answer

The route is in Active state, meaning a query is in progress.