300-410 EIGRP Troubleshooting Practice Test 2 — 15 Questions

Question 1

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 10.10.10.0/24, 1 successors, FD is 28160, Qos: 0
     via 10.1.1.2 (28160/28160), GigabitEthernet0/0
     via 10.2.2.2 (28672/28160), GigabitEthernet0/1
P 10.20.20.0/24, 1 successors, FD is 28160, Qos: 0
     via 10.2.2.2 (28160/28160), GigabitEthernet0/1
     via 10.3.3.2 (28672/28160), GigabitEthernet0/2

Based on this output, which statement is correct?

Accepted Answer

The network has redundant paths with feasible successors for both routes.. The all-links output shows all known routes, including feasible successors. For 10.10.10.0/24, there is a successor via 10.1.1.2 and a feasible successor via 10.2.2.2 (since its reported distance of 28160 is less than the FD of 28160). For 10.20.20.0/24, there is a successor via 10.2.2.2 and a feasible successor via 10.3.3.2. This indicates good redundancy.

Answer

The route to 10.20.20.0/24 has no feasible successor.

Answer

The FD for 10.10.10.0/24 is 28672.

Answer

The route to 10.10.10.0/24 is in Active state.

Question 2

A network engineer runs the following command on Router R1:

R1# show ip eigrp interfaces detail Gi0/0
EIGRP-IPv4 Interfaces for AS(100)
Interface: GigabitEthernet0/0
  Peers: 1
  Xmit Queue Un/Reliable: 0/0
  Mean SRTT: 12
  Pacing Time Un/Reliable: 0/10
  Multicast Flow Timer: 50
  Pending Routes: 0
  Hello interval: 5
  Hold time: 15
  Split horizon: Enabled
  Next multicast: 0.0.0.0
  Next broadcast: 0.0.0.0

Based on this output, what is the problem?

Accepted Answer

Split horizon is enabled, which is a normal and expected configuration.. The detail output shows split horizon is enabled on the interface. Split horizon is a loop prevention mechanism that prevents routes from being advertised out the interface they were learned on. This is normal and expected. There is no problem.

Answer

Split horizon is disabled, which could cause routing loops.

Answer

The hold time of 15 seconds is too short and may cause instability.

Answer

The interface has no peers, indicating a problem.

Question 3

A network engineer runs the following command on Router R1:

R1# show ip eigrp topology 10.50.50.0/24
EIGRP-IPv4 Topology Entry for AS(100)/ID(192.168.1.1) for 10.50.50.0/24
  State: Active, Reply status: 0, Originating router: 192.168.1.1
  Routing Descriptor Blocks:
  10.1.1.2 (GigabitEthernet0/0), from 10.1.1.2, Send flag: 0x0
      Composite metric: (4294967295/4294967295), Route is Internal
      Vector metric:
        Minimum bandwidth: 100000 Kbit
        Total delay: 100 microseconds
        Reliability: 255/255
        Load: 1/255
        Minimum MTU: 1500
        Hop count: 1

Based on this output, what is the problem?

Accepted Answer

The route is in Active state with an infinite metric, indicating that the router has lost the route and is querying for a new path.. The route to 10.50.50.0/24 is in Active state, meaning the router is actively querying for a successor. The composite metric is 4294967295 (Infinity), indicating that the route is unreachable. This is a problem because the router has lost the route and is trying to find an alternative path.

Answer

The route is passive and stable.

Answer

The metric of 4294967295 is normal for a summary route.

Answer

The hop count of 1 indicates the route is one hop away and reachable.

Question 4

Consider the following EIGRP configuration on Router R1:

router eigrp 100
 network 10.0.0.0
 passive-interface default
 no passive-interface GigabitEthernet0/0

What is the effect of this configuration?

Accepted Answer

EIGRP will form neighbor adjacencies only on GigabitEthernet0/0.. The configuration sets all interfaces to passive by default, then re-enables EIGRP on GigabitEthernet0/0. This means only GigabitEthernet0/0 will send and receive EIGRP hello packets and form adjacencies; all other interfaces will only advertise networks without forming neighbors.

Answer

EIGRP will form neighbor adjacencies on all interfaces.

Answer

EIGRP will not form any neighbor adjacencies.

Answer

EIGRP will form neighbor adjacencies on all interfaces except GigabitEthernet0/0.

Question 5

Given the following EIGRP configuration on Router R2:

router eigrp 200
 network 192.168.1.0
 network 10.0.0.0
 no auto-summary

Which statement is true about the operation of EIGRP?

Accepted Answer

EIGRP will advertise 192.168.1.0/24 and 10.0.0.0/8 as exact prefixes.. The no auto-summary command disables automatic summarization at classful boundaries, so EIGRP will advertise subnets exactly as configured under the network statements.

Answer

EIGRP will automatically summarize 192.168.1.0 to 192.168.0.0/16.

Answer

EIGRP will only advertise the classful networks 192.168.0.0/16 and 10.0.0.0/8.

Answer

EIGRP will not form neighbor adjacencies due to missing network mask.

Question 6

Examine the following EIGRP configuration on Router R3:

interface GigabitEthernet0/1
 ip bandwidth-percent eigrp 100 50

What is the effect of this command?

Accepted Answer

EIGRP will limit its control traffic to 50% of the interface bandwidth.. This command limits the EIGRP bandwidth usage on the interface to 50% of the configured interface bandwidth. It affects how much bandwidth EIGRP can use for control traffic.

Answer

EIGRP will use only 50% of the interface bandwidth for data traffic.

Answer

EIGRP will adjust the metric calculation to use 50% of the bandwidth.

Answer

EIGRP will form neighbor adjacencies only when bandwidth usage is below 50%.

Question 7

Consider the following EIGRP configuration on Router R4:

router eigrp 300
 variance 2
 network 172.16.0.0

What is the purpose of the variance command?

Accepted Answer

It allows load balancing over paths with metrics up to twice the best metric.. The variance command allows EIGRP to load-balance across multiple paths whose metric is within the variance multiplier times the best metric. A variance of 2 means paths with a metric up to twice the best metric can be used for load balancing.

Answer

It sets the maximum number of equal-cost paths to 2.

Answer

It sets the EIGRP metric weight for delay to 2.

Question 8

Given the following configuration snippet on Router R5:

router eigrp 400
 network 10.1.1.0 0.0.0.255

What is wrong with this configuration?

Accepted Answer

The configuration is correct as shown.. The network command in EIGRP uses a wildcard mask, but the mask 0.0.0.255 is correct for a /24 prefix. However, the network address 10.1.1.0 is a subnet, which is valid. There is no error; the configuration is correct.

Answer

The wildcard mask should be 255.255.255.0.

Answer

The network address should be the classful network 10.0.0.0.

Answer

The AS number 400 is invalid; EIGRP AS numbers must be between 1 and 65535.

Question 9

Examine the following EIGRP configuration on Router R6:

interface GigabitEthernet0/2
 ip hello-interval eigrp 100 15
 ip hold-time eigrp 100 45

What is the effect of these commands?

Accepted Answer

EIGRP will send hello packets every 15 seconds and wait 45 seconds before declaring a neighbor down.. These commands change the EIGRP hello interval to 15 seconds and hold time to 45 seconds on the interface for AS 100. The hold time is three times the hello interval by default, but here it is explicitly set.

Answer

EIGRP will send hello packets every 45 seconds and wait 15 seconds.

Answer

EIGRP will use the default hello interval of 5 seconds and hold time of 15 seconds.

Answer

EIGRP will not form neighbor adjacencies because the hold time is not a multiple of the hello interval.

Question 10

What is the default EIGRP hello interval on a point-to-point serial interface?

Accepted Answer

5 seconds. EIGRP uses a default hello interval of 5 seconds on most interfaces, including point-to-point serial links. On NBMA interfaces like Frame Relay, the default may be different, but for point-to-point it is 5 seconds.

Answer

10 seconds

Answer

30 seconds

Answer

60 seconds

Question 11

Which of the following is a mandatory condition for a route to be considered a feasible successor in EIGRP?

Accepted Answer

The reported distance must be less than the feasible distance.. A feasible successor must have a reported distance (RD) less than the feasible distance (FD) of the successor. This ensures the path is loop-free.

Answer

The metric must be equal to the successor's metric.

Answer

The next-hop router must be directly connected.

Answer

The route must be learned from the same AS.

Question 12

What is the default administrative distance for internal EIGRP routes?

Accepted Answer

90. Cisco IOS assigns an administrative distance of 90 to internal EIGRP routes. External EIGRP routes have a distance of 170.

Answer

110

Answer

120

Answer

170

Question 13

Which TWO commands would a network engineer use to verify that EIGRP is correctly forming neighbor adjacencies and exchanging routes on an interface? (Choose TWO.)

Accepted Answer

show ip eigrp neighbors. The 'show ip eigrp neighbors' command lists all established neighbors and their interface details, confirming adjacency. The 'show ip eigrp interfaces' command displays interfaces on which EIGRP is active and includes neighbor count, verifying that the interface is participating in EIGRP. The other commands either show routes (not neighbor state) or are not EIGRP-specific.

Answer

show ip route eigrp

Answer

show ip protocols

Answer

show ip ospf neighbor

Question 14

Which TWO statements about EIGRP stub routing are true when troubleshooting a hub-and-spoke topology? (Choose TWO.)

Accepted Answer

A stub router advertises only connected and summary routes to its neighbors.. EIGRP stub routers advertise only connected and summary routes to their neighbors, preventing them from being used as transit. The stub feature must be configured on the spoke router; the hub router does not need stub configuration. Options C and D are false because stub routers do not query for lost routes (they reply with 'Stub'), and they still advertise connected routes by default.

Answer

The stub feature is configured on the hub router to limit queries from spokes.

Answer

A stub router will send a query to its neighbors if it loses a route.

Answer

Stub routers do not advertise any connected routes unless specifically configured.

Answer

The hub router must have the stub command configured to accept stub advertisements.

Question 15

Which TWO configuration steps are required to enable EIGRP authentication between two directly connected routers? (Choose TWO.)

Accepted Answer

Configure a key chain with a key string on both routers.. EIGRP authentication requires a key chain with a key string and the authentication mode set to md5 (or hmac-sha-256) on the interface. The key chain must be defined globally, and then the interface configuration references it. The other options are incorrect because authentication is per-interface, not per-process, and the key chain name must match on both sides.

Answer

Apply the authentication mode and key chain under the EIGRP router process.

Answer

Set the same autonomous system number in the key chain configuration.

Answer

Ensure the key chain name is different on each router to prevent conflicts.