Technology
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Questions derived from the 640-801 - Cisco Certified Network Associate (single-exam option) Cisco Self-Test Software Practice Test.
Objective: Technology
SubObjective: Evaluate the characteristics of routing protocols
Item Number: 640-801.4.4.12
Single Answer, Multiple Choice
Which type of OSPF route originates within the area and describes destinations that reside in the area?
- Area routes
- External routes
- Inter-area routes
- Intra-area routes
Answer:
D. Intra-area routes
Tutorial:
Intra-area routes originate within the area and describe destinations that reside in the area.
OSPF uses the concept of areas to control the flooding of link-state updates between routers. OSPF routers notify other routers of network changes by sending link-state advertisements. The link-state advertisements are used to maintain the link-state database. When a router receives a link-state advertisement it updates its own database and propagates the update to other routers. Each router uses the Dijkstra algorithm and the link-state database to construct the shortest path tree to the destination. The destination, the next-hop to use to reach the destination, and a cost (the metric) are all stored in the IP routing table. Routes that describe destination within the area are referred to as intra-area routes. These routes are identified with an O in the routing table. Routes that originate in other areas are called inter-area routes and are identified as O IA in the routing table. Routes that are redistributed into OSPF and routing table are called external routes. External routes appear as O E1 or O E2 in the routing table.
For more information on OSPF route types, see: http://www.cisco.com/en/US/tech/tk365/technologies_white_paper09186a0080094e9e.shtml#t14
Reference:
1. ICND Student Guide v2.1 - Volume 1 - Enabling EIGRP
- EIGRP Features
2. ICND Student Guide v2.1 - Volume 1 - Enabling OSPF
- OSPF Features
