CCNA 200-301 Bulldog Practice Exam: OSPF Fundamentals

Today’s CCNA Bulldog Practice Exam tests your knowledge of vital OSPF fundamentals, including those pesky little timers and other values that can disrupt or prevent OSPF adjacencies.  Let’s get to it!

Question 1:

Will the numeric mismatch shown in the following two configs prevent an OSPF adjacency from forming (assuming everything else is just fine, that is)?   No multiple choice for this one — it’s either fine or it isn’t!

Question 2: 

How often are OSPF Hello packets multicast on an OSPF Broadcast network?

A.   Every 30 seconds.

B.   Every 10 seconds.

C.   Every 60 seconds.

D.   Every 120 seconds.

E.   OSPF Broadcast networks do not use Hello packets.

Question 3:   

When it comes to the OSPF Hello and Dead timers, do potential OSPF neighbors have to agree on both, one in particular, or neither in order for an  adjacency to form?

A.   Both of them.

B.   Only the Hello timer.

C.   Only the Dead timer.

D.   Neither timer affects OSPF adjacencies.

Question 4: 

The OSPF algorithm is typically referred to by one of two names.  Identify them both.

A.   DUAL

B.   Dijkstra

C.   OSPF

D.   SPF

E.   Diffie-Hellman

Question 5:

Which two of the following are considered to be purely Link-State protocols?

A.   OSPF

B.   EIGRP

C.   RIP Version 1

D.   RIP Version 2

E.   IS-IS

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Answer 1:   The numeric mismatch does not affect the adjacency.

The number in each of those router ospf commands is the OSPF process number, and that is a locally significant value only.  In other words, the potential neighbor doesn’t know what process number the local router is using, and that potential neighbor doesn’t even care.

Answer 2:  B.   OSPF Hello packets go out every 10 seconds on a Broadcast network type.  This partial output of show ip  ospf interface gig 0/1 verifies that timer value.

R2#show ip ospf int gig 0/1
GigabitEthernet0/1 is up, line protocol is up
Internet Address 10.1.1.2/24, Area 0, Attached via Network Statement
Process ID 22, Router ID 10.1.1.2, Network Type BROADCAST, Cost: 1
Topology-MTID Cost Disabled Shutdown Topology Name
0 1 no no Base
Transmit Delay is 1 sec, State DR, Priority 1
Designated Router (ID) 10.1.1.2, Interface address 10.1.1.2
Backup Designated router (ID) 10.1.1.1, Interface address 10.1.1.1
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5

Answer 3:  A.   Potential neighbors must agree on both the OSPF Hello and Dead timer values set on the interfaces that are attempting to form an adjacency.

Answer 4:  B, D.   The OSPF algorithm is known as both the Dijkstra algorithm and the SPF (Shortest Path First) algorithm.

Answer 5:  A, E.  Configuring IS-IS is not on the CCNA R&S exam, but it’s a very good idea to know that IS-IS and OSPF are strictly Link-State Protocols.  EIGRP is considered to be a hybrid of both Link-State and Distance Vector protocols.   Both versions of RIP are strictly Distance Vector  protocols.

That’s it for this Bulldog Practice Exam!   You’ll find literally dozens of free CCNA practice exams on this page, so go tackle a few of those and I’ll see you tomorrow with another new exam!

Chris Bryant

CCIE #12933

“The Computer Certification Bulldog”