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76.
R1, an ABR between backbone area 0 and area 1, has intra-area routes in area 0 for
10.1.1.0/24, 10.1.2.0/24, and 10.1.3.0/24. These routes have metrics of 21, 22, and 23,
respectively. An engineer then adds the area 0 range 10.1.0.0 255.255.0.0 command
under the OSPF process of R1. Which of the following are true? (Choose two.)
- A.R1 loses and then reestablishes neighborships with all neighbors.
- B.R1 no longer advertises 10.1.1.0/24 to neighbors into area 1.
- C.R1 advertises a 10.1.0.0/16 route into area 1 with a metric of 23 (largest metric).
- D.R1 advertises a 10.1.0.0/16 route into area 1 with a metric of 21 (lowest metric).
- Answer & Explanation
- Report
Answer : [B and D]
Explanation :
Explanation :
| The area range command does not cause a failure in neighborships. Because at least one intra-area subordinate subnet of 10.1.0.0/16 exists in R1, R1 both creates a summary route for 10.1.0.0/16 and stops advertising LSAs for the (three) subordinate subnets. By default, the metric of the summary is the metric of the lowest-metric component subnet. |
77.
The following output exists on Router R1, a router internal to area 1. What can you
determine as true from the output of the show ip ospf database summary command?
Routing Bit Set on this LSA LS age: 124 Options: (No TOS-capability, DC, Upward) LS Type: Summary Links (Network) Link State ID: 10.1.0.0 (summary Network Number) Advertising Router: 1.1.1.1 LS Seq Number: 80000001 Checksum: 0x878F Length: 28 Network Mask: /22 TOS: 0 Metric: 11
- A.The LSA was created by an ABR because of an area range command
- B.The LSA was created by an ASBR because of a summary-address command
- C.If created by an area range command, the best metric for a subordinate subnet on that ABR must have been 11.
- D.None of the other answers are correct
- Answer & Explanation
- Report
Answer : [D]
Explanation :
Explanation :
| The show ip ospf database summary command lists only Type 3 LSAs. The summary-address command creates Type 5 LSAs on ASBRs, ruling out one answer. The output does not specify whether the LSA was created as a summary route; all references to the word “summary” refer to Type 3 Summary LSAs. If created by an area range command, the metric defaults to be the best metric of all subordinate subnets, but it can also be explicitly set, ruling out another of the possible answers. In short, this LSA can represent a route summarized by the area range command, but that fact cannot be proved or disproved by the output as shown. |
78.
Router R1, an ASBR connected to the Internet and to backbone area 0, has been configured
with a default-information originate command. Which of the following is
true about the effects of this configuration command?
- A.R1 will always create and flood a default route into the OSPF domain
- B.R1 will create and flood an LSA for prefix/length 0.0.0.0/0 into the OSPF domain if R1’s IP routing table has a route to 0.0.0.0/0.
- C.R1 will set a flag on the LSA for the subnet between itself and one of the ISPs, noting this subnet as a default network, regardless of whether R1 has a default route.
- D.R1 will set a flag on the LSA for the subnet between itself and one of the ISPs, noting this subnet as a default network, but only if R1 has a route to 0.0.0.0/0.
- Answer & Explanation
- Report
Answer : [B]
Explanation :
Explanation :
| Without the always parameter, the default-information originate command generates an LSA for a default route, with prefix 0.0.0.0/0, but only if its own IP routing table has a route for 0.0.0.0/0. It does not flag another LSA as being used as a candidate default route. |
79.
Which of the following are true about routers internal to a totally NSSA area?
(Choose two.)
- A.Routers cannot redistribute external routes into the area.
- B.Routers should have zero Type 3 LSAs in their LSDBs.
- C.Routers should have zero Type 5 LSAs in their LSDBs
- D.Routers should learn default routes from the ABRs attached to the area.
- Answer & Explanation
- Report
Answer : [C and D]
Explanation :
Explanation :
| Both types of NSSA stubby areas allow the redistribution of external routes into an area, but these routes are advertised as Type 7 LSAs. As a totally NSSA, the ABR should flood no Type 5 LSAs into the area and flood no Type 3 LSAs into the area, except for the Type 3 LSAs used to advertise the default route into the area. As such, a router internal to a totally stubby area should see zero Type 5 LSAs and a small number of Type 3 LSAs for the default route(s) advertised by the ABR(s). |
80.
ABR R1 has been configured with an area 1 stub no-summary command. Which stubby area type is area 1?
- A.Stub/li>
- B.Totally Stuby
- C.NSSA
- D.Totally NSSA
- Answer & Explanation
- Report
Answer : [B]
Explanation :
Explanation :
| The stub keyword means either a stub area or a totally stubby area. The nosummary command means that the area is totally stubby. |
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