300-410 EIGRP Troubleshooting Practice Test 4 — 15 Questions

Question 1

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 2

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 3

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 4

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 5

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.

Question 6

What is the default EIGRP hello interval on a point-to-point serial interface with bandwidth 1544 Kbps?

Accepted Answer

5 seconds. EIGRP uses a default hello interval of 5 seconds on high-speed interfaces (bandwidth >= 1544 Kbps) and 60 seconds on low-speed interfaces (bandwidth <= 1544 Kbps).

Answer

60 seconds

Answer

10 seconds

Answer

30 seconds

Question 7

Which EIGRP packet type is used to confirm receipt of a reliable update?

Accepted Answer

ACK. EIGRP uses reliable transport for updates, queries, and replies. The receiver sends an ACK packet (a Hello packet with no data) to confirm receipt.

Answer

Hello

Answer

Update

Answer

Reply

Question 8

What is the default EIGRP hold time multiplier relative to the hello interval?

Accepted Answer

Hold time is three times the hello interval. By default, EIGRP sets the hold time to three times the hello interval. This ensures that a few missed hellos do not immediately cause neighbor loss.

Answer

Hold time equals hello interval

Answer

Hold time is twice the hello interval

Answer

Hold time is four times the hello interval

Question 9

Which of the following is the correct formula for EIGRP composite metric calculation using default K values?

Accepted Answer

metric = bandwidth + delay. With default K values (K1=1, K2=0, K3=1, K4=0, K5=0), the composite metric reduces to metric = bandwidth + delay.

Answer

metric = bandwidth * delay

Answer

metric = bandwidth + delay + reliability

Answer

metric = bandwidth + delay + load

Question 10

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 11

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 12

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 13

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 14

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 15

Drag and drop the steps to troubleshoot EIGRP neighbor adjacency formation into the correct order, from first to last.

Accepted Answer

Verify Layer 1 and Layer 2 connectivity between routers. The correct order ensures that you first verify the physical and data link layer, then check IP connectivity, confirm EIGRP is enabled on the correct interfaces, verify the autonomous system number matches, and finally check for any passive interface configuration that might block adjacency.