EIGRP practice questions

A network engineer is troubleshooting an EIGRP issue in a large enterprise network. Two routers, R1 and R2, are connected via a T1 link. R1 is learning a route to 10.0.0.0/8 from R2 with a metric of 28160, but the same route is also learned from another neighbor with a metric of 26880. The engineer notices that the route from R2 is not being installed in the routing table. What is the most likely cause?

Trap 1: The route from R2 is a feasible successor, so it is not installed…

Incorrect. Feasible successors are backup routes stored in the topology table, but the question describes a route that is not installed because a better metric route exists, not because it's a feasible successor.

Trap 2: EIGRP is using unequal-cost load balancing, so the higher metric…

Incorrect. Unequal-cost load balancing (variance) allows multiple routes with different metrics to be used, but by default only the best metric route is installed. The scenario does not mention variance configuration.

Trap 3: The route from R2 is a summary route, so it is not installed in the…

Incorrect. Summary routes can be installed in the routing table if they are the best route. The metric difference indicates a non-summary issue.

A
The route from R2 is a feasible successor, so it is not installed in the routing table.
Why wrong: Incorrect. Feasible successors are backup routes stored in the topology table, but the question describes a route that is not installed because a better metric route exists, not because it's a feasible successor.
B
EIGRP is using unequal-cost load balancing, so the higher metric route is not used.
Why wrong: Incorrect. Unequal-cost load balancing (variance) allows multiple routes with different metrics to be used, but by default only the best metric route is installed. The scenario does not mention variance configuration.
C
The route with metric 28160 is not installed because EIGRP selects the route with the lowest metric.
Correct. EIGRP installs only the route with the best (lowest) metric in the routing table. Since 26880 is lower than 28160, the route from R2 is not installed.
D
The route from R2 is a summary route, so it is not installed in the routing table.
Why wrong: Incorrect. Summary routes can be installed in the routing table if they are the best route. The metric difference indicates a non-summary issue.

Question 2hardmultiple choice

An engineer configures EIGRP on a new router in a DMVPN network. The router has a single physical interface with two subinterfaces: one for the DMVPN tunnel and one for a direct point-to-point link to a hub router. The engineer notices that EIGRP adjacencies form only on the point-to-point link, not on the DMVPN tunnel. The tunnel interface is configured with ip nhrp network-id 1 and ip nhrp nhs 10.1.1.1. What is the most likely reason?

Trap 1: The tunnel interface is not configured with the 'ip nhrp map'…

Incorrect. The 'ip nhrp map' command is used for static mapping, but NHRP dynamically learns mappings in a typical DMVPN. The adjacency issue is more likely due to EIGRP not being enabled on the tunnel.

Trap 2: The DMVPN tunnel is using a different autonomous system number than…

Incorrect. If the autonomous system numbers differ, EIGRP adjacencies would not form on any interface. The scenario states adjacencies form on the point-to-point link, so AS numbers match.

Trap 3: The tunnel interface is in a different VRF than the point-to-point…

Incorrect. While VRF mismatch can prevent adjacencies, the scenario does not mention VRF configuration. The most common cause is missing EIGRP configuration on the tunnel interface.

A
The tunnel interface is not configured with the 'ip nhrp map' command for the hub router.
Why wrong: Incorrect. The 'ip nhrp map' command is used for static mapping, but NHRP dynamically learns mappings in a typical DMVPN. The adjacency issue is more likely due to EIGRP not being enabled on the tunnel.
B
The tunnel interface is not configured with the 'ip eigrp' command under the interface configuration.
Correct. For EIGRP to form an adjacency over the tunnel interface, the interface must be included in the EIGRP process, typically with 'ip eigrp <as-number>' under the interface. Without it, EIGRP will not send or receive hello packets on that interface.
C
The DMVPN tunnel is using a different autonomous system number than the point-to-point link.
Why wrong: Incorrect. If the autonomous system numbers differ, EIGRP adjacencies would not form on any interface. The scenario states adjacencies form on the point-to-point link, so AS numbers match.
D
The tunnel interface is in a different VRF than the point-to-point link.
Why wrong: Incorrect. While VRF mismatch can prevent adjacencies, the scenario does not mention VRF configuration. The most common cause is missing EIGRP configuration on the tunnel interface.

Question 3mediummultiple choice

A network engineer is designing an EIGRP network with multiple routers. The network has a core layer where all routers are fully meshed. The engineer wants to ensure that if a link fails, EIGRP converges quickly without relying on route redistribution or static routes. The engineer configures EIGRP with default timers. However, during a failure simulation, convergence takes over 15 seconds. What is the most likely reason?

Trap 1: EIGRP is using passive interfaces on the core routers, preventing…

Incorrect. Passive interfaces prevent EIGRP from forming adjacencies, but if they are passive, no convergence would occur. The scenario implies adjacencies exist.

Trap 2: EIGRP hold timers are set to 180 seconds by default, causing slow…

Incorrect. Default hold timers are 15 seconds on LAN interfaces, not 180 seconds. The slow convergence is not due to timer defaults.

Trap 3: The engineer configured 'eigrp stub' on the core routers, which…

Incorrect. Stub routers do not propagate queries, which can speed convergence. This would not cause slow convergence.

A
EIGRP is using passive interfaces on the core routers, preventing rapid updates.
Why wrong: Incorrect. Passive interfaces prevent EIGRP from forming adjacencies, but if they are passive, no convergence would occur. The scenario implies adjacencies exist.
B
The failed link was the only feasible successor for the affected routes, causing EIGRP to go into active state and query neighbors.
Correct. When the only feasible successor fails, EIGRP transitions to active state and sends queries to all neighbors. The time to receive all replies can exceed 15 seconds, especially in large networks.
C
EIGRP hold timers are set to 180 seconds by default, causing slow detection.
Why wrong: Incorrect. Default hold timers are 15 seconds on LAN interfaces, not 180 seconds. The slow convergence is not due to timer defaults.
D
The engineer configured 'eigrp stub' on the core routers, which prevents query propagation.
Why wrong: Incorrect. Stub routers do not propagate queries, which can speed convergence. This would not cause slow convergence.

Question 4hardmultiple choice

An engineer is troubleshooting an EIGRP issue where a router is not learning a specific route from a neighbor. The engineer runs 'show ip eigrp topology all-links' and sees the route in the topology table with a feasible distance of 100 and a reported distance of 120. The neighbor's advertised distance is 80. The router's own computed distance to the network is 150. The route is not in the routing table. What is the most likely cause?

Trap 1: The route is a feasible successor, but the successor route is not…

Incorrect. A feasible successor must have a reported distance less than the feasible distance. Here, reported distance (120) is greater than feasible distance (100), so it is not a feasible successor.

Trap 2: The route is not installed because the reported distance (80) from…

Incorrect. The reported distance from the neighbor is 80, which is less than the feasible distance of 100, so it meets the feasibility condition. However, the router's computed distance is 150, which is higher than the feasible distance, but that does not prevent installation. The issue is that the route is not the best.

Trap 3: The route is not installed because EIGRP is configured for stub…

Incorrect. Stub routing only affects query propagation, not route learning. The route is in the topology table, so it is learned.

A
The route is a feasible successor, but the successor route is not present.
Why wrong: Incorrect. A feasible successor must have a reported distance less than the feasible distance. Here, reported distance (120) is greater than feasible distance (100), so it is not a feasible successor.
B
The route is not installed because the reported distance (80) from the neighbor is less than the feasible distance (100), but the router's computed distance (150) is higher.
Why wrong: Incorrect. The reported distance from the neighbor is 80, which is less than the feasible distance of 100, so it meets the feasibility condition. However, the router's computed distance is 150, which is higher than the feasible distance, but that does not prevent installation. The issue is that the route is not the best.
C
The route is not installed because the feasible distance (100) is not the best metric; the router has another route with a lower metric.
Correct. The feasible distance is 100, but if there is another route with a lower metric (e.g., 90), that route would be the successor and installed. The route with FD 100 would not be installed. The scenario implies the route is not the best.
D
The route is not installed because EIGRP is configured for stub routing, which prevents learning routes.
Why wrong: Incorrect. Stub routing only affects query propagation, not route learning. The route is in the topology table, so it is learned.

Question 5mediummultiple choice

A network engineer is configuring EIGRP on a router that connects to multiple remote sites via Frame Relay. The engineer wants to ensure that EIGRP does not form adjacencies over the Frame Relay interfaces to reduce overhead, but still wants to advertise the connected networks. The engineer applies the 'passive-interface' command to the Frame Relay interfaces. However, the remote sites stop receiving the routes. What is the most likely reason?

Trap 1: The 'passive-interface' command only affects hello packets, not…

Incorrect. The passive-interface command suppresses both hello and update packets on the interface.

Trap 2: The engineer should use the 'neighbor' command under the EIGRP…

Incorrect. While the neighbor command can be used for static neighbors, it does not solve the issue of passive-interface blocking updates. The engineer would need to remove passive-interface or use a different method.

Trap 3: The remote sites are using a different EIGRP autonomous system…

Incorrect. If AS numbers differ, no adjacency would form, but the scenario says they were receiving routes before the passive-interface command.

A
The 'passive-interface' command also prevents EIGRP from sending routing updates on that interface.
Correct. The passive-interface command suppresses both hello packets and routing updates. Therefore, the remote sites do not receive the routes.
B
The 'passive-interface' command only affects hello packets, not updates, but the remote sites are not configured correctly.
Why wrong: Incorrect. The passive-interface command suppresses both hello and update packets on the interface.
C
The engineer should use the 'neighbor' command under the EIGRP process to specify the remote routers.
Why wrong: Incorrect. While the neighbor command can be used for static neighbors, it does not solve the issue of passive-interface blocking updates. The engineer would need to remove passive-interface or use a different method.
D
The remote sites are using a different EIGRP autonomous system number.
Why wrong: Incorrect. If AS numbers differ, no adjacency would form, but the scenario says they were receiving routes before the passive-interface command.

Question 6mediummultiple choice

An engineer is troubleshooting an EIGRP convergence issue in a network with redundant links. The engineer notices that when a primary link fails, the backup link takes over immediately, but the routing table shows the route with a higher metric. The engineer wants to ensure that the backup link is used only when the primary fails, and that traffic is not load-balanced. The engineer has configured 'variance 2' on all routers. What is the most likely effect of this configuration?

Trap 1: The variance 2 command causes EIGRP to install only the best metric…

Incorrect. Variance 2 allows routes with metrics up to twice the best metric to be installed, so the backup link may be used for load balancing.

Trap 2: The variance 2 command has no effect on route installation; it only…

Incorrect. Variance directly affects which routes are installed in the routing table, not just feasible successor selection.

Trap 3: The variance 2 command is used for equal-cost load balancing only.

Incorrect. Variance is specifically for unequal-cost load balancing. Equal-cost load balancing happens by default without variance.

A
The variance 2 command causes EIGRP to install only the best metric route, so the backup link is not used.
Why wrong: Incorrect. Variance 2 allows routes with metrics up to twice the best metric to be installed, so the backup link may be used for load balancing.
B
The variance 2 command causes EIGRP to install both the primary and backup routes, resulting in unequal-cost load balancing.
Correct. With variance 2, if the backup route's metric is within twice the best metric, it will be installed and used for load balancing, which the engineer does not want.
C
The variance 2 command has no effect on route installation; it only affects the feasible successor selection.
Why wrong: Incorrect. Variance directly affects which routes are installed in the routing table, not just feasible successor selection.
D
The variance 2 command is used for equal-cost load balancing only.
Why wrong: Incorrect. Variance is specifically for unequal-cost load balancing. Equal-cost load balancing happens by default without variance.

Question 7hardmultiple choice

A network engineer is configuring EIGRP on a router that connects to a service provider network. The engineer wants to advertise a default route to internal routers. The engineer configures 'ip default-network 0.0.0.0' and redistributes a static default route into EIGRP. However, internal routers are not receiving the default route. The engineer checks the EIGRP topology table and sees the default route with a metric of 1. What is the most likely reason?

Trap 1: The static default route is not configured correctly; the engineer…

Incorrect. The static route may be configured correctly, but the issue is the method of advertising it into EIGRP.

Trap 2: The internal routers have a route to the default network with a…

Incorrect. The scenario does not mention other sources. The metric of 1 in the topology table indicates the route is present but not installed, likely due to administrative distance or other reasons.

Trap 3: The engineer needs to configure 'eigrp stub' on the router to allow…

Incorrect. Stub configuration does not affect default route advertisement; it only limits query propagation.

A
The engineer used 'ip default-network' which is not supported in EIGRP; instead, 'default-information originate' should be used.
Correct. EIGRP does not support the 'ip default-network' command. To advertise a default route, the engineer should use 'redistribute static' and optionally 'default-information originate' to inject the default route.
B
The static default route is not configured correctly; the engineer should use 'ip route 0.0.0.0 0.0.0.0 <next-hop>'.
Why wrong: Incorrect. The static route may be configured correctly, but the issue is the method of advertising it into EIGRP.
C
The internal routers have a route to the default network with a better metric from another source.
Why wrong: Incorrect. The scenario does not mention other sources. The metric of 1 in the topology table indicates the route is present but not installed, likely due to administrative distance or other reasons.
D
The engineer needs to configure 'eigrp stub' on the router to allow default route advertisement.
Why wrong: Incorrect. Stub configuration does not affect default route advertisement; it only limits query propagation.

Question 8mediummultiple choice

A network engineer is designing an EIGRP network with multiple routers in a hub-and-spoke topology. The engineer wants to ensure that the spoke routers do not become transit routers for traffic between other spokes. The engineer configures 'eigrp stub' on the spoke routers. However, after configuration, the spoke routers stop learning some routes from the hub. What is the most likely reason?

Trap 1: The 'eigrp stub' command prevents the spoke from learning routes…

Incorrect. The stub command affects what the spoke advertises, not what it learns. Spoke routers can still learn routes from the hub.

Trap 2: The hub router is also configured as stub, which prevents route…

Incorrect. If the hub is stub, it would not advertise routes to spokes, but the scenario implies the hub was working before.

Trap 3: The spoke routers have a different EIGRP autonomous system number…

Incorrect. If AS numbers differ, no adjacency would form, but the scenario says they were learning routes before.

A
The spoke routers are configured with 'eigrp stub receive-only', which prevents them from advertising any routes, so the hub does not have routes to the spoke's networks.
Correct. The 'receive-only' keyword prevents the spoke from advertising any routes, including its connected networks. The hub then cannot reach the spoke's networks, and the spoke may not learn routes that depend on those advertisements.
B
The 'eigrp stub' command prevents the spoke from learning routes from the hub.
Why wrong: Incorrect. The stub command affects what the spoke advertises, not what it learns. Spoke routers can still learn routes from the hub.
C
The hub router is also configured as stub, which prevents route propagation.
Why wrong: Incorrect. If the hub is stub, it would not advertise routes to spokes, but the scenario implies the hub was working before.
D
The spoke routers have a different EIGRP autonomous system number than the hub.
Why wrong: Incorrect. If AS numbers differ, no adjacency would form, but the scenario says they were learning routes before.

Question 9easymultiple choice

A network engineer is troubleshooting an EIGRP issue where two routers, R1 and R2, are directly connected. R1 shows an EIGRP adjacency with R2, but R2 does not show an adjacency with R1. The engineer checks the interface configurations and finds that R1 has 'ip authentication mode eigrp 1 md5' and 'ip authentication key-chain eigrp 1 MYKEY' configured, while R2 has no authentication configured. What is the most likely cause?

Trap 1: R2 will automatically learn the authentication key from R1 and form…

Incorrect. Authentication keys are not learned dynamically; they must be configured manually.

Trap 2: R1 will form an adjacency with R2 because authentication is…

Incorrect. If authentication is configured on one side, it is enforced; the other side must also have authentication configured.

Trap 3: The adjacency will form but only for routes that are not…

Incorrect. Authentication applies to all EIGRP packets; if it fails, no adjacency forms.

A
R1 has authentication configured, but R2 does not, so R1 will reject R2's hello packets, and no adjacency forms.
Correct. EIGRP authentication requires both sides to have matching authentication. Since R2 does not have authentication, R1 will discard R2's hello packets, preventing adjacency.
B
R2 will automatically learn the authentication key from R1 and form an adjacency.
Why wrong: Incorrect. Authentication keys are not learned dynamically; they must be configured manually.
C
R1 will form an adjacency with R2 because authentication is optional.
Why wrong: Incorrect. If authentication is configured on one side, it is enforced; the other side must also have authentication configured.
D
The adjacency will form but only for routes that are not authenticated.
Why wrong: Incorrect. Authentication applies to all EIGRP packets; if it fails, no adjacency forms.

Question 10mediummultiple choice

A network engineer runs the following command on Router R1:

R1# show ip eigrp neighbors

EIGRP-IPv4 Neighbors for AS(100) H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num 0 192.168.1.2 Gi0/0 13 00:12:34 12 100 0 45 1 10.1.1.2 Gi0/1 12 00:10:20 15 120 0 32

Based on this output, what can be concluded?

Trap 1: Both neighbors are using MD5 authentication.

The output does not display authentication status; authentication is not shown in the neighbor table.

Trap 2: Neighbor 192.168.1.2 has a higher metric than 10.1.1.2.

The neighbor table does not show metrics; metrics are shown in the topology table.

Trap 3: Router R1 is using EIGRP named mode.

The output shows 'EIGRP-IPv4 Neighbors for AS(100)', which is classic mode; named mode would show 'EIGRP-IPv4 VR' or similar.

A
Both neighbors are using MD5 authentication.
Why wrong: The output does not display authentication status; authentication is not shown in the neighbor table.
B
Neighbor 192.168.1.2 has a higher metric than 10.1.1.2.
Why wrong: The neighbor table does not show metrics; metrics are shown in the topology table.
C
Both neighbors are fully established and exchanging routing information.
The 'Q Cnt' of 0 and valid uptime indicate stable adjacencies.
D
Router R1 is using EIGRP named mode.
Why wrong: The output shows 'EIGRP-IPv4 Neighbors for AS(100)', which is classic mode; named mode would show 'EIGRP-IPv4 VR' or similar.

Question 11mediummultiple choice

A network engineer runs the following command on Router R1:

R1# show ip eigrp topology

EIGRP-IPv4 Topology Table for AS(100)/ID(192.168.1.1) Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - reply Status, s - sia Status

P 10.1.1.0/24, 1 successors, FD is 1310720 via 192.168.1.2 (1310720/1310720), GigabitEthernet0/0 P 10.2.2.0/24, 1 successors, FD is 1310720 via 192.168.1.2 (1310720/1310720), GigabitEthernet0/0 P 10.3.3.0/24, 1 successors, FD is 1310720 via 192.168.1.2 (1310720/1310720), GigabitEthernet0/0

Based on this output, what can be concluded?

Trap 1: All routes have a feasible successor.

A feasible successor requires the reported distance to be less than the feasible distance; here they are equal, so no feasible successor.

Trap 2: The routes are in Active state, meaning the router is querying for…

The 'P' code indicates Passive state, not Active.

Trap 3: The router is using EIGRP stub routing.

The output does not indicate stub configuration; stub behavior is not visible in the topology table.

A
All routes have a feasible successor.
Why wrong: A feasible successor requires the reported distance to be less than the feasible distance; here they are equal, so no feasible successor.
B
The routes are in Active state, meaning the router is querying for alternate paths.
Why wrong: The 'P' code indicates Passive state, not Active.
C
Each route has exactly one successor and no feasible successor.
The output shows one successor per route and the RD equals the FD, so no feasible successor.
D
The router is using EIGRP stub routing.
Why wrong: The output does not indicate stub configuration; stub behavior is not visible in the topology table.

Question 12mediummultiple choice

A network engineer runs the following command on Router R1:

R1# show ip eigrp interfaces detail

EIGRP-IPv4 Interfaces for AS(100)

Interface: GigabitEthernet0/0

Mtu: 1500, Bandwidth: 1000000 Kbit, Delay: 100 microseconds Reliability: 255/255, Load: 1/255, Min MTU: 1500 Hello interval: 5 sec, Hold time: 15 sec Next hello in: 3 secs Passive interface: No Split horizon: Enabled Authentication: None

Neighbor count: 1

Interface: GigabitEthernet0/1

Mtu: 1500, Bandwidth: 100000 Kbit, Delay: 1000 microseconds Reliability: 255/255, Load: 1/255, Min MTU: 1500 Hello interval: 5 sec, Hold time: 15 sec Next hello in: 1 secs Passive interface: No Split horizon: Enabled Authentication: None

Neighbor count: 1

Based on this output, what can be concluded?

Trap 1: Both interfaces have the same metric weight for bandwidth and delay.

Metric weights are not shown here; they are set by the 'metric weights' command globally.

Trap 2: Interface Gi0/1 is configured as a passive interface.

The output explicitly says 'Passive interface: No'.

Trap 3: EIGRP authentication is enabled on both interfaces.

Authentication is set to None.

A
Both interfaces have the same metric weight for bandwidth and delay.
Why wrong: Metric weights are not shown here; they are set by the 'metric weights' command globally.
B
GigabitEthernet0/1 will have a higher EIGRP metric than GigabitEthernet0/0 for the same prefix.
EIGRP metric uses bandwidth and delay; lower bandwidth and higher delay increase the metric.
C
Interface Gi0/1 is configured as a passive interface.
Why wrong: The output explicitly says 'Passive interface: No'.
D
EIGRP authentication is enabled on both interfaces.
Why wrong: Authentication is set to None.

Question 13hardmultiple choice

A network engineer runs the following command on Router R1:

R1# show ip eigrp traffic

EIGRP-IPv4 Traffic Statistics for AS(100) Hellos sent/received: 1000/950 Updates sent/received: 45/40 Queries sent/received: 2/3 Replies sent/received: 3/2 Acks sent/received: 50/48 Input queue high water mark: 1 Input queue depth: 0 Total packets sent: 1100 Total packets received: 1043

Based on this output, what can be concluded?

Trap 1: The router has experienced many route flaps.

Route flaps would generate many updates and queries; the numbers are low.

Trap 2: The router is using EIGRP stub to suppress queries.

Stub routers would not send queries; but the router has sent 2 queries, so it is not stub.

Trap 3: There is a high packet loss on the network.

Packet loss would cause retransmissions and increased traffic; the numbers are balanced.

A
The router has experienced many route flaps.
Why wrong: Route flaps would generate many updates and queries; the numbers are low.
B
The network is stable with few topology changes.
Low query and reply counts indicate stable topology.
C
The router is using EIGRP stub to suppress queries.
Why wrong: Stub routers would not send queries; but the router has sent 2 queries, so it is not stub.
D
There is a high packet loss on the network.
Why wrong: Packet loss would cause retransmissions and increased traffic; the numbers are balanced.

Question 14hardmultiple choice

A network engineer runs the following command on Router R1:

R1# show ip eigrp topology 10.1.1.0/24

EIGRP-IPv4 Topology Entry for AS(100)/ID(192.168.1.1) for 10.1.1.0/24 State: Passive, Reply status: 0, Originating router: 192.168.1.1 Routing Descriptor Blocks:

0.0.0.0 (Null0), from 0.0.0.0, Send flag: 0x0

Composite metric: (128256/0), Route is Internal Vector metric: Minimum bandwidth: 1000000 Kbit Total delay: 100 microseconds Reliability: 255/255 Load: 1/255 Minimum MTU: 1500 Hop count: 0

192.168.1.2 (GigabitEthernet0/0), from 192.168.1.2, Send flag: 0x0

Composite metric: (1310720/128256), Route is Internal Vector metric: Minimum bandwidth: 1000000 Kbit Total delay: 1100 microseconds Reliability: 255/255 Load: 1/255 Minimum MTU: 1500 Hop count: 1

Based on this output, what can be concluded?

Trap 1: The route 10.1.1.0/24 is learned from neighbor 192.168.1.2 and is…

The successor is the connected route (Null0) with metric 128256, not the learned route.

Trap 2: The router has a feasible successor for this route.

The reported distance from the neighbor equals the feasible distance, so it does not meet the feasibility condition (RD < FD).

Trap 3: The router is in Active state for this route.

The state is Passive.

A
The route 10.1.1.0/24 is learned from neighbor 192.168.1.2 and is the successor.
Why wrong: The successor is the connected route (Null0) with metric 128256, not the learned route.
B
The router has a feasible successor for this route.
Why wrong: The reported distance from the neighbor equals the feasible distance, so it does not meet the feasibility condition (RD < FD).
C
The route is directly connected on Router R1.
The Null0 entry with metric 128256/0 indicates a connected route.
D
The router is in Active state for this route.
Why wrong: The state is Passive.

Question 15mediummultiple choice

A network engineer runs the following command on Router R1:

R1# debug eigrp packets hello

EIGRP: Received HELLO on Gi0/0 nbr 192.168.1.2 AS 100, Flags 0x0, Seq 0/0 interfaceQ 0/0 EIGRP: Sending HELLO on Gi0/0 AS 100, Flags 0x0, Seq 0/0 interfaceQ 0/0 EIGRP: Received HELLO on Gi0/1 nbr 10.1.1.2 AS 100, Flags 0x0, Seq 0/0 interfaceQ 0/0 EIGRP: Sending HELLO on Gi0/1 AS 100, Flags 0x0, Seq 0/0 interfaceQ 0/0

Based on this output, what can be concluded?

Trap 1: EIGRP is using MD5 authentication between neighbors.

Authentication would show 'auth' or 'digest' in the debug output; it is not present.

Trap 2: There is a K-value mismatch between R1 and its neighbors.

K-value mismatch would cause neighbor adjacency failure; the debug shows successful hello exchange.

Trap 3: The router is using EIGRP named mode.

Named mode would show 'IPv4-EIGRP' or similar; the debug shows 'EIGRP' with AS number.

A
EIGRP is using MD5 authentication between neighbors.
Why wrong: Authentication would show 'auth' or 'digest' in the debug output; it is not present.
B
The hello packets are being exchanged normally without any issues.
The debug shows consistent sending and receiving of hellos with no errors.
C
There is a K-value mismatch between R1 and its neighbors.
Why wrong: K-value mismatch would cause neighbor adjacency failure; the debug shows successful hello exchange.
D
The router is using EIGRP named mode.
Why wrong: Named mode would show 'IPv4-EIGRP' or similar; the debug shows 'EIGRP' with AS number.

Question 16hardmultiple choice

A network engineer runs the following command on Router R1:

R1# show ip eigrp neighbors detail

EIGRP-IPv4 Neighbors for AS(100) H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num 0 192.168.1.2 Gi0/0 13 00:12:34 12 100 0 45 Version 2.0/2.0, Retrans: 0, Retry: 0, Maxseq: 0 Prefixes: 3 Topology ids: 0 Authentication: None Topology: base (0x0)

Based on this output, what can be concluded?

Trap 1: The neighbor is using EIGRP version 1.

The version is shown as 2.0/2.0.

Trap 2: There is a high number of retransmissions indicating packet loss.

Retransmissions are 0.

Trap 3: The neighbor is using MD5 authentication.

Authentication is None.

A
The neighbor is using EIGRP version 1.
Why wrong: The version is shown as 2.0/2.0.
B
The neighbor has advertised 3 prefixes to R1.
The 'Prefixes: 3' field indicates the number of prefixes learned from this neighbor.
C
There is a high number of retransmissions indicating packet loss.
Why wrong: Retransmissions are 0.
D
The neighbor is using MD5 authentication.
Why wrong: Authentication is None.

Question 17mediummultiple choice

A network engineer runs the following command on Router R1:

R1# show ip eigrp interfaces

EIGRP-IPv4 Interfaces for AS(100)

Interface                   Peers    Xmit Queue   Mean   Pacing Time   Multicast    Pending

Un/Reliable SRTT Un/Reliable Flow Timer Routes Gi0/0 1 0/0 12 0/10 50 0 Gi0/1 1 0/0 15 0/10 55 0

Based on this output, what can be concluded?

Trap 1: Both interfaces have pending routes to send.

Pending Routes is 0 for both.

Trap 2: The router is using EIGRP named mode.

The output shows 'EIGRP-IPv4 Interfaces for AS(100)', which is classic mode.

Trap 3: There is a queue backlog on Gi0/0.

Xmit Queue is 0/0, indicating no backlog.

A
Interface Gi0/1 has higher latency than Gi0/0.
The Mean SRTT is higher on Gi0/1 (15 ms) compared to Gi0/0 (12 ms), indicating higher round-trip time.
B
Both interfaces have pending routes to send.
Why wrong: Pending Routes is 0 for both.
C
The router is using EIGRP named mode.
Why wrong: The output shows 'EIGRP-IPv4 Interfaces for AS(100)', which is classic mode.
D
There is a queue backlog on Gi0/0.
Why wrong: Xmit Queue is 0/0, indicating no backlog.

Question 18hardmultiple choice

A network engineer runs the following command on Router R1:

R1# show ip eigrp topology all-links

EIGRP-IPv4 Topology Table for AS(100)/ID(192.168.1.1) Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - reply Status, s - sia Status

P 10.1.1.0/24, 1 successors, FD is 1310720, serno 5 via 192.168.1.2 (1310720/1310720), GigabitEthernet0/0 via 10.2.2.2 (1587200/1310720), GigabitEthernet0/1 P 10.2.2.0/24, 1 successors, FD is 1310720, serno 6 via 192.168.1.2 (1310720/1310720), GigabitEthernet0/0 via 10.2.2.2 (1587200/1310720), GigabitEthernet0/1

Based on this output, what can be concluded?

Trap 1: Both routes have a feasible successor via 10.2.2.2.

The RD from 10.2.2.2 equals the FD, so it does not meet the feasibility condition.

Trap 2: The route 10.1.1.0/24 has two successors.

There is only one successor (FD is 1310720, and only one path has that metric).

Trap 3: The alternate path via 10.2.2.2 will be used immediately if the…

Since it is not a feasible successor, the router must go Active and query before using it.

A
Both routes have a feasible successor via 10.2.2.2.
Why wrong: The RD from 10.2.2.2 equals the FD, so it does not meet the feasibility condition.
B
The route 10.1.1.0/24 has two successors.
Why wrong: There is only one successor (FD is 1310720, and only one path has that metric).
C
The alternate path via 10.2.2.2 will be used immediately if the successor fails.
Why wrong: Since it is not a feasible successor, the router must go Active and query before using it.
D
The router has two paths to 10.1.1.0/24, but only one is in the routing table.
Only the successor is installed in the routing table; the other path is not used unless the successor fails and queries are sent.

Question 19mediummultiple choice

Consider the following EIGRP configuration on a Cisco IOS router:

router eigrp 100
 network 10.0.0.0
 passive-interface default
 no passive-interface GigabitEthernet0/1

What is the effect of this configuration?

Trap 1: EIGRP hellos are sent on all interfaces, but GigabitEthernet0/1 is…

Incorrect. The 'passive-interface default' command prevents hellos on all interfaces unless explicitly overridden.

Trap 2: Only the network 10.0.0.0 is advertised, and all interfaces are…

Incorrect. The network statement and passive-interface commands are independent; the passive-interface command affects hello behavior, not network advertisement.

Trap 3: EIGRP will only form adjacencies on interfaces with an IP address…

Incorrect. The passive-interface command does not filter based on network statements; it applies to all interfaces regardless of IP address.

A
All interfaces except GigabitEthernet0/1 are passive and will not form EIGRP adjacencies.
Correct. The default passive setting applies to all interfaces, and the exception is made only for GigabitEthernet0/1.
B
EIGRP hellos are sent on all interfaces, but GigabitEthernet0/1 is prevented from forming adjacencies.
Why wrong: Incorrect. The 'passive-interface default' command prevents hellos on all interfaces unless explicitly overridden.
C
Only the network 10.0.0.0 is advertised, and all interfaces are passive.
Why wrong: Incorrect. The network statement and passive-interface commands are independent; the passive-interface command affects hello behavior, not network advertisement.
D
EIGRP will only form adjacencies on interfaces with an IP address in the 10.0.0.0/8 range.
Why wrong: Incorrect. The passive-interface command does not filter based on network statements; it applies to all interfaces regardless of IP address.

Question 20mediummultiple choice

Given the following EIGRP configuration on a router:

router eigrp 200
 network 192.168.1.0 0.0.0.255
 network 10.0.0.0

Which statement about this configuration is true?

Trap 1: Both network statements are classful and will enable EIGRP on all…

Incorrect. The first network statement includes a wildcard mask, making it not classful.

Trap 2: EIGRP will only be enabled on interfaces with an IP address in the…

Incorrect. The second network statement will also enable EIGRP on interfaces in the 10.0.0.0/8 range.

Trap 3: This configuration will cause an error because wildcard masks are…

Incorrect. Wildcard masks are allowed in EIGRP network statements in classic mode.

A
EIGRP will be enabled on any interface with an IP address in the 10.0.0.0/8 range, and only on interfaces with an IP address in the 192.168.1.0/24 range.
Correct. The first network statement uses a wildcard mask to specify the exact subnet, while the second is classful.
B
Both network statements are classful and will enable EIGRP on all interfaces with IP addresses in the 192.168.0.0/16 and 10.0.0.0/8 ranges.
Why wrong: Incorrect. The first network statement includes a wildcard mask, making it not classful.
C
EIGRP will only be enabled on interfaces with an IP address in the 192.168.1.0/24 range.
Why wrong: Incorrect. The second network statement will also enable EIGRP on interfaces in the 10.0.0.0/8 range.
D
This configuration will cause an error because wildcard masks are not allowed in EIGRP network statements.
Why wrong: Incorrect. Wildcard masks are allowed in EIGRP network statements in classic mode.