江浙沪招生考试网

11. Which of these statements about OSPF external LSAs (type 5) is correct?
A. External LSAs (type 5) are automatically changed to type 1 LSAs at ASBRs.
B. Type 5 LSAs are route summaries describing routes to networks outside the OSPF Autonomous System.
C. OSPF external LSAs are automatically flooded into all OSPF areas, unlike type 7 LSAs, which require
that redistribution be configured.
D. External network LSAs (type 5) redistributed from other routing protocols into OSPF are not permitted to
flood into a stub area.
E. OSPF external LSAs can be flooded into an NSSA area if redistributed from other routing protocols into
OSPF and if the subnets parameter is used with the redistribute command.
Answer: D
12. Which two of these best describe an OSPF stub area? (Choose two.)
A. All routers in a stub area must be configured as stub.
B. Each stub area always has an ASBR attached to it.
C. A stub area will not accept routes belonging to an external AS.
D. Only summary routes from an external AS can be injected into a stub area.
E. To reach outside networks, the routers in a stub area use a default route which is injected into the area
by the ASBR.
Answer: AC
13. Refer to the exhibit. Which statement best describes an OSPF not-so-stubby area (NSSA)?
A. Redistributed RIP routes (from Area 2) will be allowed into Area 1 as O E1 routes.
B. Type 5 external LSAs generated by the NSSAABR are the only type of LSAs allowed in an NSSA.
C. A default route is required on the NSSAABR to access external networks attached to Area 1.
D. An NSSA is a feature specific to Cisco that reduces the number of routes in the routing table.
E. Type 5 external LSAs are not allowed in NSSA areas, so NSSA ASBRs generate type 7 NSSA external
LSAs instead, which remain within the NSSA.
Answer: E
14. Which of these statements best describes how neighbor adjacencies are formed in a multi-access
OSPF network?
A. The router with the highest priority will become the DR.
B. Only those routers with the Cisco default priority of 0 are eligible to become the DR or BDR.
C. The router with the highest loopback address will become the DR if two or more routers have the same
priority.
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D. The router with the lowest Router ID will become the DR and the router with the next lowest Router ID
will become the BDR.
E. Election of the DR and BDR begins only after a router that wants to become either the DR or BDR enters
the ExStart state.
Answer: A
15. An OSPF router is becoming active in a multi-access network and discovers its neighbors. Which
statement is correct?
A. If the router becoming active has a higher priority than some elected routers, it may influence an election
but will not force an election to override an active DR or BDR.
B. If a DR and a BDR already exist and the router becoming active has the same priority and a higher
loopback address than either of them, it will force a new election.
C. If a DR and a BDR already exist and the router becoming active has a lower router ID than either of them,
it will force a new election.
D. If there is a DR but not a BDR, and the router becoming active has the same priority as an already active
router, the router with the lowest router ID will become the BDR.
E. If there is a DR but not a BDR, and the router becoming active has the same priority as an already active
router, the router with the highest loopback address will become the BDR.
Answer: A
16. Which three of these statements correctly describe type 2 LSAs (network link advertisements)?
(Choose three.)
A. Network LSAs are generated by the DR.
B. Network LSAs are flooded only in their originating areas.
C. A network LSA lists all attached routers including the DR.
D. Every router in an OSPF area generates type 2 LSAs, as well as type 1 LSAs.
E. The link-state ID of the type 2 LSA is the loopback address of the DR.
F.When a network LSA reaches an ABR it is converted to a type 5 LSA (AS external LSA) and then flooded
to other areas.
Answer: ABC