CCNA IP Routing

Question 1

What is the administrative distance of OSPF?

Answer 1

110

Question 2

What is the administrative distance of a directly connected route?

Answer 2

0

Question 3

What is the administrative distance of a static route?

Answer 3

1

Question 4

What is the administrative distance of BGP external routes?

Answer 4

20

Question 5

What is the administrative distance of EIGRP?

Answer 5

90

Question 6

What is the administrative distance of BGP internal routes?

Answer 6

200

Question 7

What is the administrative distance of RIP?

Answer 7

120

Question 8

Where does a router store all the OSPF LSAs it knows about?

Answer 8

The Link State Database (LSDB)

Question 9

In OSPF, what is the default LSA aging timer?

Answer 9

30 minutes

Question 10

To what multicast address are OSPF Hello messages sent?

Answer 10

224.0.0.5

Question 11

If two OSPF neighbors are in “2-way” state, what has happened? What has NOT happened?

Answer 11

Both routers see each other’s RID and their parameters match. They have not yet exchanged LSAs.

Question 12

An OSPF LSA is sent in what type of packet?

Answer 12

LSU (Link State Update)

Question 13

If a router is missing an LSA from its neighbor, what does it send?

Answer 13

A Link-State Request packet

Question 14

In OSPF, what does a “full” state represent?

Answer 14

Two neighbors have exchanged all known LSAs.

Question 15

What is the OSPF “All SPF DRs” multicast address?

Answer 15

224.0.0.6

Question 16

In what condition is “2-way” the normal end state for OSPF neighbors?

Answer 16

When they’re non-DR or non-BDR on a given LAN. They won’t exchange full databases with other non-DR routers, just with the DR and BDR.

Question 17

In OSPF, what is the difference between a “neighbor” and a “fully adjacent neighbor”?

Answer 17

A neighbor will be in a 2-way state; an adjacent or fully adjacent neighbor will be in a Full state.

Question 18

List three types of OSPF LSAs.

Answer 18

1) Router LSA
2) Network LSA (on networks with a DR)
3) Summary LSA (from other areas)

Question 19

To determine the OSPF router ID, the router will by default choose…

Answer 19

The highest working loopback address, followed by the highest working interface (non-loopback) address

Question 20

What show command will display the router’s post-Dykstra, pre-routing table SPF calculation results?

Answer 20

show ip ospf rib

Question 21

After the OSPF process has run Dykstra, what determines if a route gets put into the routing table?

Answer 21

The administrative distance - if the router knows about a route from a “better” source, it will use that over the OSPF route.

Question 22

The OSPF process can be stopped and restarted with what command?

Answer 22

clear ip ospf process

Question 23

OSPF interface costs can be manually set between what two values?

Answer 23

1 and 65,535

Question 24

What command sets a global baseline for OSPF interface cost based on speed?

Answer 24

auto-cost reference-bandwidth

Question 25

By default, how many equal-cost paths can OSPF put into the routing table for one route?

Answer 25

4 (although apparently this varies depending on router platform?)

Question 26

What command changes the maximum number of equal-cost paths OSPF can put into the routing table?

Answer 26

maximum-paths

Question 27

The OSPF router with the (highest/lowest) priority will win the DR election. If priorities are equal, the router with the (highest/lowest) RID will win.

Answer 27

highest, highest

Question 28

What does the OSPF dead timer do?

Answer 28

Tells the router how long to wait before believing a neighbor has failed (usually 4x the hello timer, 40s by default)

Question 29

What is the default OSPF Hello timer?

Answer 29

10s

Question 30

If a pair of OSPF routers are configured with Broadcast on one side and Point-to-Point on the other, what happens?

Answer 30

The routers form a full neighbor relationship, exchange LSAs, but do not put the routes in their routing tables.