Dynamic Routing Protocols - Configuring OSPF

Question 1

When you configure OSPF on an interface, you must specific an area, True or False?

Answer 1

1. True

Question 2

Areas can divide an OSPF topology into small sections, True or False?

Answer 2

1. True
   a. If you have just one area, use Area 0 - Backbone area

Question 3

OSPF areas are 32 bits in length, True or False?

Answer 3

1. True

Question 4

What command would you use to configure interface xe-0/1/5.0 in OSPF area 0?

Answer 4

1. set protocols ospf area 0 interface xe-0/1/5.0

Question 5

What is the default timer for OSPF hellos?

Answer 5

1. 10 seconds

Question 6

What is the default dead timer for OSPF?

Answer 6

1. 40 seconds

Question 7

What is the multicast address for AllOSPFRouters?

Answer 7

1. 224.0.0.5

Question 8

What is the multicast address for designated and backup designated routers?

Answer 8

1. 224.0.0.6

Question 9

What command displays a device’s OSPF neighbors if an adjancey has been established?

Answer 9

1. show ospf neighbor
   a. Use detail to see the total uptime

Question 10

What command do you use to view only the ospf routes in a routing table?

Answer 10

1. show route protocol ospf

Question 11

What is the default route preference for OSPF?

Answer 11

1. 10

Question 12

OSPF advertises two things by default, what are they?

Answer 12

1. Prefixes on interfaces configured for OSPF
2. Prefixes learned by OSPF from other routers

Question 13

How do you enable OSPF on an interface, but stop it from sending hello messages?

Answer 13

1. You set the OSPF attribute on the interface as passive.
   a. ex. set protocols ospf area 0 interface xe-0/1/1.0 passive
   b. OSPF will recongize the subnet on the interface and advertise the subnet, but will not send hello messages, therefore prohibiting adjancies on the interface.

Question 14

How do you advertise a static route into OSPF?

Answer 14

1. You create a ‘routing policy’ to take the static route out of the routing table and export it into OSPF.
   a. Routing policies advertise prefixes between protocols
   b. Some vendors call this process ‘redistribution’.

Question 15

What version of OSPF advertises only IPv4 prefixes?

Answer 15

1. OSPFv2
   a. Configured with the keyword ‘ospf’
   b. Uses ospf on the Junos CLI

Question 16

What version of OSPF can advertise IPv6 on it’s own or advertise IPv4 and IPv6 at the same time?

Answer 16

1. OSPFv3
   a. Configured with the keyword ‘ospf3’
   b. Uses ospf3 on the Junos CLI

Question 17

What similaries are there between OSPFv2 and OSPFv3?

Answer 17

1. Both have link-state databases
2. Both generate LSA’s (Link State Advertisements)
3. Both use metrics