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46.
An engineer plans to configure summary routes with the ip summary-address
eigrp asn prefix mask command. Which of the following, when added to such a
command, would create a summary that includes all four of the following subnets:
10.1.100.0/25, 10.1.101.96/27, 10.1.101.224/28, and 10.1.100.128 /25?
- A.10.1.0.0 255.255.192.0
- B.10.1.64.0 255.255.192.0
- C.10.1.100.0 255.255.255.0
- D.10.1.98.0 255.255.252.0
- Answer & Explanation
- Report
Answer : [B]
Explanation :
Explanation :
| 10.1.0.0/18 implies a range of 10.1.0.0–10.1.63.255, which includes none of the four subnets. 10.1.64.0/18 implies a range of 10.1.64.0–10.1.127.255, which includes all subnets. 10.1.100.0/24 implies a range of 10.1.100.0–10.1.100.255, which leaves out two of the subnets. Finally, 10.1.98.0/22 does not actually represent a summary. Instead, 10.1.96.0/22 represents a range of 10.1.96.0–10.1.99.255, with 10.1.98.0 as listed in answer D being an IP address in that range. As such, Cisco IOS would actually accept the command, would change the parameter from 10.1.98.0 to 10.1.96.0, and would not include the four listed subnets. |
47.
R1 has five working interfaces, with EIGRP neighbors existing off each interface. R1
has routes for subnets 10.1.1.0/24, 10.1.2.0/24, and 10.1.3.0/24, with EIGRP integer
metrics of roughly 1 million, 2 million, and 3 million, respectively. An engineer then
adds the ip summary-address eigrp 1 10.1.0.0 255.255.0.0 command to interface
Fa0/0. Which of the following is true?
- A.R1 loses and then reestablishes neighborships with all neighbors
- B.R1 no longer advertises 10.1.1.0/24 to neighbors connected to Fa0/0.
- C.R1 advertises a 10.1.0.0/16 route out Fa0/0, with metric of around 3 million (largest metric of component subnets).
- D.R1 advertises a 10.1.0.0/16 route out Fa0/0, with metric of around 2 million (median metric of component subnets).
- Answer & Explanation
- Report
Answer : [B]
Explanation :
Explanation :
| The ip summary-address command does reset neighborships, but only on the interface under which it is configured. After those neighborships come up, R1 will advertise the summary route, but none of the subordinate routes inside that summary. The summary route will use a metric equal to the metric of the lowest metric subordinate route, approximately 1,000,000 in this case. |
48.
In a lab, R1 connects to R2, which connects to R3. R1 and R2 each have several
working interfaces, all assigned addresses in Class A network 10.0.0.0. Router R3 has
some working interfaces in Class A network 10.0.0.0, and others in Class B network
172.16.0.0. The engineer experiments with the auto-summary command on R2 and
R3, enabling and disabling the command in various combinations. Which of the following
combinations will result in R1 seeing a route for 172.16.0.0 /16, instead of the
individual subnets of Class B network 172.16.0.0? (Choose two.)
- A.auto-summary on R2 and no auto-summary on R3
- B.auto-summary on R2 and auto-summary on R3
- C.no auto-summary on R2 and no auto-summary on R3
- D.no auto-summary on R2 and auto-summary on R3.
- Answer & Explanation
- Report
Answer : [B]and[D]
Explanation :
Explanation :
| R2 has interfaces only in Class A network 10.0.0.0, so the auto-summary setting has no effect. R3 has interfaces in both Class A network 10.0.0.0 and Class B network 172.16.0.0, so auto-summary causes R3 to summarize all subnets of 172.16.0.0/16 as a summary route when advertising to R2. |
49.
Router R1 exists in an enterprise that uses EIGRP as its routing protocol. The show
ip route command output on Router R1 lists the following phrase: “Gateway of last
resort is 1.1.1.1 to network 2.0.0.0.” Which of the following is most likely to have
caused this output to occur on R1?
- A.R1 has been configured with an ip default-network 2.0.0.0 command
- B.R1 has been configured with an ip route 0.0.0.0 0.0.0.0 1.1.1.1 command.
- C.R1 has been configured with an ip route 2.0.0.0 255.0.0.0 1.1.1.1 command.
- D.Another router has been configured with an ip default-network 2.0.0.0 command.
- Answer & Explanation
- Report
Answer : [D]
Explanation :
Explanation :
| The phrase quoted in the question means that R1 is using its route for Class A network 2.0.0.0 to decide where to send packets by default. R1’s route for network 2.0.0.0 must have 1.1.1.1 as its next-hop router. This phrase occurs when EIGRP has learned a route for Class A network 2.0.0.0 that has been flagged as a candidate default route by another router. The router flagging a route as a candidate default route, using the ip default-network command, does not actually use the route as its default route. |
50.
Enterprise Router R1 connects an enterprise to the Internet. R1 needs to create and
advertise a default route into the enterprise using EIGRP. The engineer creating the
implementation plan has chosen to base this default route on the ip route command,
rather than using ip default-network . Which of the following are not useful steps
with this style of default route configuration? (Choose two.)
- A.Create the default route on R1 using the ip route 0.0.0.0 0.0.0.0 outgoinginterface command.
- B.Redistribute the statically configured default route.
- C.Disable auto-summary
- D.Configure the network 0.0.0.0 command
- E.Ensure that R1 has no manually configured summary routes using the ip summary-address eigrp command.
- Answer & Explanation
- Report
Answer : [C][E]
Explanation :
Explanation :
| With the suggested configuration style, the static route must first be configured statically, as shown in answer A. Then, either this route must be redistributed as a static route into EIGRP (answer B) or pulled into EIGRP by virtue of the network 0.0.0.0 EIGRP subcommand (answer D). The other two options have no effect on default route creation and advertisement. |
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