EIGRP and OSPF

Question: If routers in a single area are configured with the same priority value, what value does a router use for the OSPF Router ID in the absence of a loopback interface?
[A].

The lowest IP address of any physical interface

[B].

The highest IP address of any physical interface

[C].

The lowest IP address of any logical interface

[D].

The highest IP address of any logical interface

Answer: Option B

Explanation:

At the moment of OSPF process startup, the highest IP address on any active interface will be the Router ID (RID) of the router. If you have a loopback interface configured (logical interface), then that will override the interface IP address and become the RID of the router automatically.

Question: With which network type will OSPF establish router adjacencies but not perform the DR/BDR election process?
[A].

Point-to-point

[B].

Backbone area 0

[C].

Broadcast multi-access

[D].

Non-broadcast multi-access

Answer: Option A

Explanation:

No DR is assigned on any type of point-to-point link. No DR/BDR is assigned on the NBMA point-to-multipoint due to the hub/spoke topology. DR and BDR are elected on broadcast and non-broadcast multi-access networks. Frame Relay is a non-broadcast multi-access (NBMA) network by default.

Question: You need the IP address of the devices with which the router has established an adjacency. Also, the retransmit interval and the queue counts for the adjacent routers need to be checked. What command will display the required information?
[A].

show ip eigrp adjacency

[B].

show ip eigrp topology

[C].

show ip eigrp interfaces

[D].

show ip eigrp neighbors

Answer: Option D

Explanation:

The show ip eigrp neighbors command allows you to check the IP addresses as well as the retransmit interval and queue counts for the neighbors that have established an adjacency.

Question: A network administrator needs to configure a router with a distance-vector protocol that allows classless routing. Which of the following satisfies those requirements?
[A].

IGRP

[B].

OSPF

[C].

RIPv1

[D].

EIGRP

Answer: Option D

Explanation:

In this question, we’re calling EIGRP just plain old distance vector. EIGRP is an “advanced” distance-vector routing protocol, sometimes called a hybrid routing protocol because it uses the characteristics of both distance-vector and link-state routing protocols.

Question: Which of the following network types have a designated router and a backup designated router assigned?

[A].

1, 2 and 3

[B].

1 and 3

[C].

3 and 4

[D].

All of the above

Answer: Option B

Explanation:

No DR is assigned on any type of point-to-point link. No DR/BDR is assigned on the NBMA point-to-multipoint due to the hub/spoke topology. DR and BDR are elected on broadcast and non-broadcast multi-access networks. Frame Relay is a non-Broadcast Multi-Access (NBMA) network by default.

Question: Which of the following protocols support VLSM, summarization, and discontiguous networking?

[A].

1 and 4

[B].

2 and 5

[C].

3, 4 and 6

[D].

All of the above

Answer: Option C

Explanation:

RIPv1 and IGRP are true distance-vector routing protocols and can’t do much, really-except build and maintain routing tables and use a lot of bandwidth! RIPv2, EIGRP, and OSPF build and maintain routing tables, but they also provide classless routing, which allows for VLSM, summarization, and discontiguous networking.

Question: You get a call from a network administrator who tells you that he typed the following into his router:

[A].

The wildcard mask is incorrect.

[B].

The OSPF area is wrong.

[C].

The OSPF Process ID is incorrect.

[D].

The AS configuration is wrong.

Answer: Option A

Explanation:

The administrator typed in the wrong wildcard mask configuration. The wildcard should have been 0.0.0.255.

Question: Your company is running IGRP using an AS of 10. You want to configure EIGRP on the network but want to migrate slowly to EIGRP and don’t want to configure redistribution. What command would allow you to migrate over time to EIGRP without configuring redistribution?
[A].

router eigrp 11

[B].

router eigrp 10

[C].

router eigrp 10 redistribute igrp

[D].

router igrp combine eigrp 10

Answer: Option B

Explanation:

If you enable EIGRP on a router with the same autonomous system (AS) number, EIGRP will automatically redistribute IGRP into EIGRP. You will see the IGRP injected routes as external (EX) routes with an EIGRP AD of 170. This is a nice feature that lets you migrate slowly to EIGRP with no extra configuration.