What is the purpose of an OSPF virtual link?
To connect a nonzero area to the backbone if the nonzero area becomes disconnected from the backbone. A virtual link can also be used if the backbone, or area 0, becomes discontiguous.
How is the OSPF cost of an interface calculated?
By default, the cost of an OSPF interface is 1 OO,OOO,OOO/(Interface Bandwidth). The constant 100,000,000 can be changed using the auto-cost reference-bandwidth command.
The following OSPF routes originate in OSPF area 1:
What is the command to summarize these routes on the ABR between area 1 and the backbone?
Area 1 range
Why are intra-area summary routes not allowed?
OSPF databases on routers in the same area must be identical. If route summarization was allowed within an area, some routers would have specific routes and some routers would have summary routes for routers in the area. If this were allowed, the databases for the area would never agree.
Using the following routing table, determine the best route to reach the host at address
Network Output Interface Serial 0 Ethernet 1 Ethernet 2 because it matches more network bits than Network and do not match on the network address.