EIGRP Questions

Here you will find answers to EIGRP Questions

Note: If you are not sure about EIGRP, please read my EIGRP tutorial

Question 1

A router has learned three possible routes that could be used to reach a destination network.
One route is from EIGRP and has a composite metric of 20514560. Another route is from OSPF with a metric of 782. The last is from RIPv2 and has a metric of 4.

Which route or routes will the router install in the routing table?

A. the OSPF route
B. the EIGRP route
C. the RIPv2 route
D. all three routes
E. the OSPF and RIPv2 routes

Answer: B

Explanation

Regardless of the metric value, EIGRP has the lowest Administrative Distance (AD) so it will be used and routes learned from EIGRP will be installed in the routing table. Some popular ADs are listed below:

+ Static route: 1
+ RIPv1 & RIPv2: 120
+ IGRP & EIGRP: 90
+ OSPF: 110

Question 2

HQ_Router# show ip protocols

Routing Protocol is “eigrp 109”
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Default networks flagged in outgoing updates
Default networks accepted from incoming updates
EIGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0
EIGRP maximum hopcount 100
EIGRP maximum metric variance 1
Redistributing: eigrp 109
Automatic network summarization is in effect
Automatic address summarization: 20.0.0.0/0 for FastEthernet0/1
Summarizing with metric 28160 172.30.0.0/16 for FastEthernet0/0
Summarizing with metric 28160
Maximum path: 4
Routing for Networks:
20.0.0.0
172.30.0.0
192.160.1.0
Routing Information Sources:
Gateway Distance Last Update
20.10.10.2 90 260796
172.30.10.2 90 454765
Distance: internal 90 external 170

How many paths can the EIGRP routing process use to forward packets from HQ_Router to a neighbor router?

A. two equal-cost paths
B. two unequal-cost paths
C. three equal-cost paths
D. three unequal-cost paths
E. four equal-cost paths
F. four unequal-cost paths

Answer: E

Explanation

Because the “EIGRP maximum metric variance” is 1 so only equal-cost paths are used.
The “Maximum path” is 4 so EIGRP can use up to 4 paths to forward packets.

Therefore EIGRP can only use four equal-cost paths -> E is correct.

Notice: This question has another version with “EIGRP maximum metric variance” is set to a value greater than 1 than the answer should be “four unequal-cost paths” can be used.

Question 3

Fabrikant Incorporated is a worldwide finance provider. The network uses EIGRP as its routing protocol throughout the corporation. The network administrator does not understand the convergence of EIGRP. Using the output of the show ip eigrp topology all-links command, answer the administrators questions:

Switch1# show ip eigrp topology all-links

Which three EIGRP routes will be installed for the 172.20.3.128 /25 and 172.20.2.0/24 networks? (choose three)

A. 172.20.3.128 /25 [90/28160] via 172.20.1.2 01:26:35. FastEthernet0/2
B. 172.20.3.128 /25 [90/30720] via 172.20.3.2 01:26:35. FastEthernet0/3
C. 172.20.3.128 /25 [90/30720] via 172.20.10.2 01:26:35. FastEthernet0/1
D. 172.20.2.0 /24 [90/30720] via 172.20.10.2 02:10:11. FastEthernet0/1
E. 172.20.2.0 /24 [90/28160] via 172.20.10.2 02:10:11. FastEthernet0/1
F. 172.20.2.0 /24 [90/33280] via 172.20.3.2 02:10:11. FastEthernet0/1

Answer: B C D

Explanation

There is a similar question posted at http://www.digitaltut.com/route-eigrp-simlet. Please read the explanation there and try to answer this question.

Question 4 (same question as question 3)

Switch1# show ip eigrp topology all-links

Which three networks does the Switch1 device have feasible successors for? (Choose three)

A. 172.20.10.0 /30
B. 172.20.1.0 /24
C. 172.20.2.0 /24
D. 172.20.3.0 /25
E. 172.20.3.128/25
F. 10.69.0.0/24

Answer: A C F

Question 5

A network administrator is troubleshooting an EIGRP problem on a router and needs to confirm the IP addresses of the devices with which the router has established adjacency. The retransmit interval and the queue counts for the adjacent routers also need to be checked.

What command will display the required information?

A. Router# show ip eigrp topology
B. Router# show ip eigrp interfaces
C. Router# show ip eigrp adjacency
D. Router# show ip eigrp neighbors

Answer: D

Explanation

Below is an example of the “show ip eigrp neighbors” command (from 9tut.com)

Question 6

As a Cisco technician, you need to know EIGRP protocol very well. Which of the following is true about EIGRP successor routes? (Choose two)

A. A successor route is used by EIGRP to forward traffic to a destination.
B. Successor routes are saved in the topology table to be used if the primary route fails.
C. Successor routes are flagged as “active” in the routing table.
D. A successor route may be backed up by a feasible successor route.
E. Successor routes are stored in the neighbor table following the discovery process.

Answer: A D

Question 7

Problems may occur when a routing protocol tries to identify the next hop in discontinuous networks in the IP addressing scheme. But some routing protocols may minimize the effects of the problems.

Which are these routing protocols? (Choose three)

A. EIGRP
B. VLSM
C. OSPF
D. RIP v2

Answer: A C D

Explanation

Classless routing protocols can be used in discontinuous networks as they do send the subnet mask in their updates so Variable Length Subnet Masks (VLSMs) are supported.

Question 8

Glencoe#show ip protocol
Routing Protocol is “eigrp 478”
— output omitted —
Redistributing: eigrp 478
Automatic network summarization is not in effect
Maximum path: 4
Routing for Networks:
172.26.168.128/26
172.26.169.0/26
Routing Information Sources:
Gateway Distance Last Update
172.26.168.129 90 01:01:59
Distance: internal 90 external 170

The EIGRP configuration in the Glencoe router uses a single network statement.
From the output shown in the graphic, which network statement would advertise these networks in EIGRP?

A. network 172.26.168.128 area 478
B. network 172.26.0.0
C. network 172.26.168.0 area 478
D. network 172.26.168.128 0.0.0.127

Answer: B

Question 9

What will a router do if it does not have EIGRP feasible successor route to a destination network and the successor route to that destination network is in active status?

A. It broadcasts Hello packets to all routers in the network to re-establish neighbor adjacencies.
B. It routes all traffic that is addressed to the destination network to the interface indicated in the routing table.
C. It sends a multicast query packet to all adjacent neighbors requesting available routing paths to the destination network.
D. It sends a copy of its neighbor table to all adjacent routers.

Answer: C

Question 10

The company uses EIGRP as the routing protocol.

R3# show ip route
Gateway of last resort is not set
192 168.10.0/24 is variably subnetted, 6 subnets, 2 masks
D 192.168. 10.64/26 [90/2195456] via 192.168.10.9, 00:03:31, Serial0/0
D 192.168.10.0/30 [90/2681856] via 192.168.10.9, 00:03:31, Serial0/0
C 192.168.10.4/30 is directly connected, Serial 0/1
C 192.168.10.8/30 is directly connected, Serial 0/0
C 192.168.10.192/26 is directly connected, FastEthernet0/0
D 192.168.10.128/26 [90/2195456] via 192.168.10.5,00:03 31, Serial 0/1

What path will packets take from a host on 192.168.10.192/26 network to a host on the LAN attached to router R1?

A. The path of the packets will be R3 to R2 to R1.
B. The path of the packets will be R3 to R1 to R2.
C. The path of the packets will be both R3 to R2 to R1 and R3 to R1.
D. The path of the packets will be R3 to R1.

Answer: D

Explanation

From the line “D 192.168. 10.64/26 [90/2195456] via 192.168.10.9, 00:03:31, Serial0/0″ we can see the IP address 192.168.10.9 belongs to network 192.168.10.8/30 and this network is between R1 and R3 -> Packet from 192.168.10.192/26 network destined to a host on the LAN attached to router R1 will go directly from R3 to R1.