OSPF

Question 1

What does the default-information originate and redistribute {network} command do?

Answer 1

configures OSPF to inject a router’s default external route into OSPF (router becomes the default route in OSPF), router is then considered an ASBR (Autonomous System Boundary Router).

Question 2

What are Autonomous System Boundary Routers (ASBR)?

Answer 2

ASBRs redistributes routes from other routing protocols into the OSPF domain

Question 3

Which type of load balancing does OSPF support.

Answer 3

Equal-cost load balancing.

EIGRP supports unequal-cost load balancing

Question 4

What does OSPF use to calculate its cost metric?

Answer 4

OSPF uses bandwidth to calculate its cost metric. Higher the bandwidth, the lower the cost

Question 5

What are the 5 OSPF network types?

Answer 5

Broadcast
Nonbroadcast
Point-to-point
Point-to-multipoint broadcast
Point-to-multipoint nonbroadcast

Question 6

Describe OSPF Broadcast network types

Answer 6

Elections are performed
multicast updates are sent, manual config of neighbor routers NOT required.
Hello = 10s, Dead = 40s
Default on Fiber Distributed Data Interface (FDDI) and all Ethernet

Question 7

Describe OSPF Nonbroadcast network types

Answer 7

DR and BDR elections, no multicast, manual config of neighbors for unicast updates
Hello = 30s, Dead = 120s
Default on Frame Relay and X.25

Question 8

Describe OSPF Point-to-point network types?

Answer 8

No DR and BDR elections, multicast updates, manual config of neighbors NOT required
Hello = 10s, Dead = 40s
Default on High-Level Data Link Control (HDLC) and Point-to Point Protocol (PPP)

Question 9

Describe OSPF Point-to-multipoint broadcast network types?

Answer 9

No DR and BDR elections, multicast updates, manual config of neighbors NOT required
Hello = 30s, Dead = 120s

Question 10

Describe OSPF Point-to-multipoint nonbroadcast network types?

Answer 10

No DR and BDR elections, no multicast, manual config of neighbors required
Hello = 30s, Dead = 120s

Question 11

(OSPF) What must happen for routers to form an adjacency?

Answer 11

Router IDs must be unique (if not manually configured: will be highest loopback. If not configured: will be highest IP interface)
(EIGRP Router IDs must match)
OSPF Area must match
In the same subnet
Dead timer should not match Hello timer