OSPF config

Question 1

What command starts OSPF configuration in router config mode?

Answer 1

router ospf <process-id>

Question 2

What command advertises a network in OSPF?

Answer 2

network <ip> <wildcard-mask> area <area-id>

Question 3

What command sets the OSPF router ID manually?

Answer 3

router-id <x.x.x.x> inside OSPF router config mode

Question 4

What command makes an interface passive in OSPF?

Answer 4

passive-interface <interface>

Question 5

What command makes all interfaces passive by default in OSPF?

Answer 5

passive-interface default

Question 6

What command sets the OSPF cost on an interface?

Answer 6

ip ospf cost <value>

Question 7

What command sets the OSPF reference bandwidth?

Answer 7

auto-cost reference-bandwidth <value> in router OSPF config mode

Question 8

What command prevents a router from becoming DR or BDR?

Answer 8

ip ospf priority 0 on the interface

Question 9

What command sets OSPF router priority for DR election?

Answer 9

ip ospf priority <0-255>

Question 10

What command enables OSPF plaintext authentication on an interface?

Answer 10

ip ospf authentication and ip ospf authentication-key <key>

Question 11

What command enables MD5 authentication for OSPF?

Answer 11

ip ospf authentication message-digest

Question 12

How is an MD5 key configured for OSPF?

Answer 12

ip ospf message-digest-key <key-id> md5 <key>

Question 13

What command sets the OSPF network type to point-to-point?

Answer 13

ip ospf network point-to-point

Question 14

What command sets the OSPF network type to non-broadcast?

Answer 14

ip ospf network non-broadcast

Question 15

Which network type requires manual neighbor configuration in OSPF?

Answer 15

Non-broadcast and point-to-multipoint non-broadcast

Question 16

What command adds a manual OSPF neighbor?

Answer 16

neighbor <ip-address> [priority <value>] in router OSPF mode

Question 17

Why is manual neighbor configuration needed?

Answer 17

For non-broadcast OSPF network types that do not support multicast discovery.

Question 18

What command makes an area a stub?

Answer 18

area <area-id> stub

Question 19

What command makes an area totally stubby?

Answer 19

area <area-id> stub no-summary

Question 20

What command makes an area NSSA?

Answer 20

area <area-id> nssa

Question 21

What command makes an area a Totally NSSA?

Answer 21

area <area-id> nssa no-summary

Question 22

How do you assign an OSPF process to an interface using ‘ip ospf’?

Answer 22

ip ospf <process-id> area <area-id> on the interface

Question 23

What command verifies OSPF neighbors?

Answer 23

show ip ospf neighbor

Question 24

What command verifies OSPF routes?

Answer 24

show ip route ospf

Question 25

What command displays the OSPF interface configuration?

Answer 25

`show ip ospf interface`

Question 26

What command displays the OSPF database?

Answer 26

`show ip ospf database`

Question 27

Why would OSPF neighbors get stuck in INIT state?

Answer 27

The local router received a Hello but was not listed in the neighbor’s Hello packet.

Question 28

Why would OSPF neighbors get stuck in EXSTART?

Answer 28

Router ID conflict or MTU mismatch.

Question 29

What causes OSPF to fail forming a neighbor relationship?

Answer 29

Mismatched area ID, Hello/Dead timers, subnet, or authentication settings.