Route Summarization practice questions

A network engineer is troubleshooting a connectivity issue between two branches connected via a WAN link. Router R1 (10.1.0.0/16) is summarizing its directly connected subnets (10.1.1.0/24, 10.1.2.0/24, 10.1.3.0/24) as a single 10.1.0.0/16 route to Router R2 via EIGRP. Users at R2 report that they cannot reach the 10.1.4.0/24 subnet, which was recently added to R1. What is the most likely cause of the problem?

Trap 1: The summary route 10.1.0.0/16 was configured manually, and the new…

Incorrect because 10.1.4.0/24 is within the 10.1.0.0/16 range. The summary should include it.

Trap 2: The WAN link is down, causing R2 to lose the summary route.

Incorrect. The symptom is specific to the new subnet; other subnets are reachable, so the link is likely up.

Trap 3: The engineer forgot to configure the summary address on the…

Incorrect. A single summary address covers all subnets; no additional summary is needed for the new subnet.

A
The summary route 10.1.0.0/16 was configured manually, and the new subnet 10.1.4.0/24 is not within the summary range because the mask is too specific.
Why wrong: Incorrect because 10.1.4.0/24 is within the 10.1.0.0/16 range. The summary should include it.
B
The new subnet 10.1.4.0/24 was not advertised because the summary address command suppresses more specific routes, but the summary itself is not being generated due to a missing network statement under the EIGRP process.
Correct. In EIGRP, a manually configured summary address suppresses the advertisement of more specific routes and generates the summary only if the component routes exist. If the new subnet is not in the EIGRP network, the summary may not be generated or the specific route is missing.
C
The WAN link is down, causing R2 to lose the summary route.
Why wrong: Incorrect. The symptom is specific to the new subnet; other subnets are reachable, so the link is likely up.
D
The engineer forgot to configure the summary address on the interface facing R2 for the new subnet.
Why wrong: Incorrect. A single summary address covers all subnets; no additional summary is needed for the new subnet.

Question 2hardmultiple choice

A network engineer is troubleshooting an OSPF network where routers R1, R2, and R3 are in area 0. R1 has a summary route 192.168.0.0/22 configured on its interface to R2, summarizing four /24 subnets (192.168.0.0/24 through 192.168.3.0/24). After the configuration, R3 loses connectivity to the 192.168.0.0/24 subnet, although other subnets are reachable. What is the most likely cause?

Trap 1: The summary route 192.168.0.0/22 is being advertised with a metric…

Incorrect. A metric of 0 is valid; it would not cause loss of connectivity to one specific subnet.

Trap 2: The summary-address command was applied on R1 as an ABR, but R1 is…

Incorrect. The summary-address command on an ABR is valid for summarizing routes from other areas, but if R1 is not an ABR, the command may not work as expected, but this would affect all subnets.

Trap 3: The 192.168.0.0/24 subnet is not included in the summary because…

Incorrect. 192.168.0.0/24 is within the /22 range, so it should be included.

A
The summary route 192.168.0.0/22 is being advertised with a metric of 0, causing R3 to prefer a less specific route from another source.
Why wrong: Incorrect. A metric of 0 is valid; it would not cause loss of connectivity to one specific subnet.
B
The summary-address command was applied on R1 as an ABR, but R1 is not an ABR because it is in area 0 only; the command is ignored.
Why wrong: Incorrect. The summary-address command on an ABR is valid for summarizing routes from other areas, but if R1 is not an ABR, the command may not work as expected, but this would affect all subnets.
C
The 192.168.0.0/24 subnet is not included in the summary because the summary mask is /22, but the subnet mask of 192.168.0.0/24 is not contiguous with the others due to a configuration error.
Why wrong: Incorrect. 192.168.0.0/24 is within the /22 range, so it should be included.
D
The summary-address command on R1 is configured with the 'not-advertise' keyword, suppressing the summary but not the specific routes, causing a routing black hole for the 192.168.0.0/24 subnet.
Correct. The 'not-advertise' keyword in OSPF summary-address prevents the summary from being advertised, but the specific routes may still be suppressed if the command is misapplied, leading to loss of connectivity to the specific subnet.

Question 3mediummultiple choice

A network engineer is troubleshooting BGP route summarization on a border router that advertises a summary route 172.16.0.0/16 to an ISP neighbor. The engineer notices that the ISP is receiving the summary route but also receiving the more specific routes (172.16.1.0/24, 172.16.2.0/24), causing suboptimal routing. What should the engineer do to ensure only the summary route is advertised?

Trap 1: Configure the 'network' command for the summary route and remove…

Incorrect. Removing network statements for specific subnets may cause them to not be injected into BGP, but the summary route may still not be generated.

Trap 2: Apply a route-map to the neighbor to filter out the specific routes…

Incorrect. While filtering can work, it is not the best practice; the aggregate-address command is designed for this purpose.

Trap 3: Configure the 'summary-address' command under the BGP process.

Incorrect. The 'summary-address' command is used in OSPF, not BGP.

A
Configure the 'network' command for the summary route and remove the network statements for the specific subnets.
Why wrong: Incorrect. Removing network statements for specific subnets may cause them to not be injected into BGP, but the summary route may still not be generated.
B
Use the 'aggregate-address 172.16.0.0 255.255.0.0 summary-only' command under the BGP process.
Correct. The aggregate-address with summary-only keyword creates the summary and suppresses all more specific routes from being advertised.
C
Apply a route-map to the neighbor to filter out the specific routes using an ACL.
Why wrong: Incorrect. While filtering can work, it is not the best practice; the aggregate-address command is designed for this purpose.
D
Configure the 'summary-address' command under the BGP process.
Why wrong: Incorrect. The 'summary-address' command is used in OSPF, not BGP.

Question 4hardmultiple choice

A network engineer is troubleshooting a redistribution issue between EIGRP and OSPF. Router R1 redistributes EIGRP routes into OSPF. The engineer configured a summary route 10.0.0.0/8 using the 'summary-address' command under the OSPF process. After the configuration, OSPF neighbors lose connectivity to the 10.1.0.0/16 subnet, which is one of the component routes. What is the most likely cause?

Trap 1: The summary-address command on R1 is configured with the 'tag'…

Incorrect. The tag keyword does not cause the summary to be ignored; it is used for route tagging.

Trap 2: The OSPF neighbor relationship is down due to a mismatch in area…

Incorrect. The symptom is specific to one subnet; neighbor relationships are likely up.

Trap 3: The engineer forgot to configure the 'network' command for the…

Incorrect. The summary-address command does not require a network statement; it is applied to redistributed routes.

A
The summary-address command on R1 is configured with the 'tag' keyword, causing the summary to be ignored by other routers.
Why wrong: Incorrect. The tag keyword does not cause the summary to be ignored; it is used for route tagging.
B
The summary route 10.0.0.0/8 is not being generated because the component routes are not all present in the OSPF database.
Correct. In OSPF, the summary-address command generates a summary only if at least one component route exists in the OSPF database. If the component route is missing due to redistribution issues, the summary may not be generated, and the specific routes may be suppressed.
C
The OSPF neighbor relationship is down due to a mismatch in area IDs.
Why wrong: Incorrect. The symptom is specific to one subnet; neighbor relationships are likely up.
D
The engineer forgot to configure the 'network' command for the summary route under OSPF.
Why wrong: Incorrect. The summary-address command does not require a network statement; it is applied to redistributed routes.

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Question 5mediummultiple choice

A network engineer is troubleshooting a route summarization issue in a network using RIP. Router R1 is configured with the 'ip summary-address rip 192.168.0.0 255.255.252.0' command on its serial interface. After the configuration, R2, which is connected via that interface, can no longer reach the 192.168.1.0/24 subnet, although other subnets within the summary are reachable. What is the most likely cause?

Trap 1: The 192.168.1.0/24 subnet is not directly connected to R1, so it…

Incorrect. RIP can summarize routes learned from other interfaces as well.

Trap 2: The summary route 192.168.0.0/22 is being advertised with a higher…

Incorrect. The summary route would replace the specific routes, not compete with them.

Trap 3: The summary address command was applied on the wrong interface,…

Incorrect. The summary is applied on a specific interface; it does not affect other interfaces.

A
The 192.168.1.0/24 subnet is not directly connected to R1, so it cannot be summarized.
Why wrong: Incorrect. RIP can summarize routes learned from other interfaces as well.
B
The summary route 192.168.0.0/22 is being advertised with a higher metric than the specific routes, causing R2 to prefer a different path.
Why wrong: Incorrect. The summary route would replace the specific routes, not compete with them.
C
The summary address command was applied on the wrong interface, causing the summary to be sent out all interfaces, including the one facing the 192.168.1.0/24 subnet's origin.
Why wrong: Incorrect. The summary is applied on a specific interface; it does not affect other interfaces.
D
The 192.168.1.0/24 subnet is not included in the summary range because the summary mask is /22, but the subnet's network address is 192.168.1.0, which is within the range, but the RIP process may have a split-horizon issue preventing the route from being advertised.
Correct. In RIP, split horizon prevents a route from being advertised out the interface it was learned on. If the 192.168.1.0/24 subnet was learned on the same interface where the summary is applied, it will not be advertised, causing loss of connectivity.

Question 6hardmultiple choice

A network engineer is troubleshooting an OSPF network where an ABR (R1) is configured with the 'area 1 range 10.0.0.0 255.255.0.0' command to summarize routes from area 1 into area 0. After the configuration, routers in area 0 lose connectivity to the 10.0.1.0/24 subnet, although the summary route 10.0.0.0/16 is present in their routing tables. What is the most likely cause?

Trap 1: The summary route 10.0.0.0/16 is being advertised with a metric of…

Incorrect. A metric of 0 is valid and would not cause loss of connectivity to a specific subnet.

Trap 2: The ABR is not generating the summary route because the component…

Incorrect. The area range command summarizes routes within the specified area.

Trap 3: The 10.0.1.0/24 subnet is not included in the summary range because…

Incorrect. 10.0.1.0/24 is within the 10.0.0.0/16 range.

A
The summary route 10.0.0.0/16 is being advertised with a metric of 0, causing routers to prefer a default route instead.
Why wrong: Incorrect. A metric of 0 is valid and would not cause loss of connectivity to a specific subnet.
B
The ABR is not generating the summary route because the component routes are not all in the same area.
Why wrong: Incorrect. The area range command summarizes routes within the specified area.
C
The 10.0.1.0/24 subnet is not included in the summary range because the range command uses a network mask that does not match the subnet's network address.
Why wrong: Incorrect. 10.0.1.0/24 is within the 10.0.0.0/16 range.
D
The summary route is installed, but the next-hop IP address for the summary route is not reachable from routers in area 0, causing traffic to be dropped.
Correct. In OSPF, the summary route's next hop is set to the ABR's interface IP. If that interface is down or the path is not reachable, traffic to the summary may fail, and since specific routes are suppressed, connectivity to the subnet is lost.

Question 7mediummultiple choice

A network engineer is troubleshooting a BGP route summarization issue. Router R1 is configured with the 'aggregate-address 192.168.0.0 255.255.252.0' command without any keywords. The engineer notices that the ISP neighbor is receiving both the aggregate route and the more specific routes (192.168.0.0/24, 192.168.1.0/24, etc.), causing the ISP to prefer the specific routes. What should the engineer do to ensure the aggregate route is preferred?

Trap 1: Remove the network statements for the specific subnets from the BGP…

Incorrect. Removing network statements may cause the specific routes to not be injected, but the aggregate may still not be preferred if the specific routes are learned via other means.

Trap 2: Configure a route-map to set a higher local preference on the…

Incorrect. Local preference is used for outbound traffic; it does not affect what the ISP prefers.

Trap 3: Use the 'aggregate-address' command with the 'as-set' keyword.

Incorrect. The as-set keyword preserves AS_PATH information but does not suppress specific routes.

A
Add the 'summary-only' keyword to the aggregate-address command.
Correct. The summary-only keyword suppresses the advertisement of more specific routes, leaving only the aggregate route.
B
Remove the network statements for the specific subnets from the BGP process.
Why wrong: Incorrect. Removing network statements may cause the specific routes to not be injected, but the aggregate may still not be preferred if the specific routes are learned via other means.
C
Configure a route-map to set a higher local preference on the aggregate route.
Why wrong: Incorrect. Local preference is used for outbound traffic; it does not affect what the ISP prefers.
D
Use the 'aggregate-address' command with the 'as-set' keyword.
Why wrong: Incorrect. The as-set keyword preserves AS_PATH information but does not suppress specific routes.

Question 8mediummultiple choice

A network engineer is troubleshooting an EIGRP network where route summarization is configured. Router R1 has the 'ip summary-address eigrp 100 10.0.0.0 255.0.0.0' command on its interface facing R2. After the configuration, R2 loses connectivity to the 10.1.0.0/16 subnet, which is one of the component routes. The engineer checks the routing table on R2 and sees the summary route 10.0.0.0/8 but not the specific route. What is the most likely cause?

Trap 1: The summary route 10.0.0.0/8 is being advertised with a metric of…

Incorrect. A metric of infinity would prevent the route from being installed, but the specific routes would still be suppressed.

Trap 2: The 10.1.0.0/16 subnet is not directly connected to R1, so it…

Incorrect. EIGRP can summarize routes learned from any interface.

Trap 3: The summary address command was applied on the wrong interface,…

Incorrect. The summary is applied on a specific interface; it does not affect other interfaces.

A
The summary route 10.0.0.0/8 is being advertised with a metric of infinity, causing it to be ignored.
Why wrong: Incorrect. A metric of infinity would prevent the route from being installed, but the specific routes would still be suppressed.
B
The 10.1.0.0/16 subnet is not directly connected to R1, so it cannot be summarized.
Why wrong: Incorrect. EIGRP can summarize routes learned from any interface.
C
The summary address command was applied on the wrong interface, causing the summary to be sent out all interfaces, including the one facing the 10.1.0.0/16 subnet's origin.
Why wrong: Incorrect. The summary is applied on a specific interface; it does not affect other interfaces.
D
The 10.1.0.0/16 subnet is not included in the summary range because the summary mask is /8, but the subnet's network address is 10.1.0.0, which is within the range, but the EIGRP process may have a split-horizon issue or the component route is not in the EIGRP topology table.
Correct. If the component route is not in the EIGRP topology table (e.g., due to a missing network statement or a passive interface), the summary route may still be generated, but the specific route is not advertised, causing loss of connectivity.

Question 9hardmultiple choice

A network engineer is troubleshooting a route summarization issue in a network using OSPFv3. Router R1 is configured with the 'ipv6 summary-address 2001:db8:0:1::/64' command under the OSPFv3 process. After the configuration, routers in the same area lose connectivity to the 2001:db8:0:1:1::/80 subnet, which is one of the component routes. What is the most likely cause?

Trap 1: The OSPFv3 process is not enabled on the interface facing the…

Incorrect. The issue is with summarization, not with OSPFv3 enablement.

Trap 2: The summary-address command should be applied on the interface, not…

Incorrect. In OSPFv3, the summary-address command is configured under the router ospfv3 process.

Trap 3: The 2001:db8:0:1:1::/80 subnet is not in the OSPFv3 database…

Incorrect. The summary-address command works for redistributed routes as well.

A
The summary-address command in OSPFv3 requires a prefix-length, not a mask; the engineer used a /64 prefix, which is too specific to summarize the /80 subnet.
Correct. The summary-address command in OSPFv3 uses a prefix length. A /64 summary will not include a /80 subnet because the /80 is more specific and falls outside the summary range.
B
The OSPFv3 process is not enabled on the interface facing the 2001:db8:0:1:1::/80 subnet.
Why wrong: Incorrect. The issue is with summarization, not with OSPFv3 enablement.
C
The summary-address command should be applied on the interface, not under the OSPFv3 process.
Why wrong: Incorrect. In OSPFv3, the summary-address command is configured under the router ospfv3 process.
D
The 2001:db8:0:1:1::/80 subnet is not in the OSPFv3 database because it is redistributed from another protocol.
Why wrong: Incorrect. The summary-address command works for redistributed routes as well.

Question 10mediummultiple choice

A network engineer runs the following command on Router R1:

R1# show ip eigrp topology 10.0.0.0 255.255.252.0

IP-EIGRP (AS 100): Topology entry for 10.0.0.0/22 State: Passive, Origin: Internal, Metric [90/2172416], Tag 0 Number of successors: 1 FD is 2172416, Serno: 5 Route is Summary Advertised by R2 (via Serial0/0/0) Reply status: 0

Based on this output, what is true about the route 10.0.0.0/22?

Trap 1: The route is a summary route generated by R1.

The route is advertised by R2, not generated by R1.

Trap 2: The route is an external route redistributed into EIGRP.

The origin is Internal, not External.

Trap 3: The route is in active state and being queried.

The state is Passive, not Active.

A
The route is a summary route generated by R1.
Why wrong: The route is advertised by R2, not generated by R1.
B
The route is a summary route learned from R2.
The output shows 'Advertised by R2' and 'Route is Summary', indicating it is a summary route received from neighbor R2.
C
The route is an external route redistributed into EIGRP.
Why wrong: The origin is Internal, not External.
D
The route is in active state and being queried.
Why wrong: The state is Passive, not Active.

Question 11mediummultiple choice

A network engineer runs the following command on Router R1:

R1# show ip route 172.16.0.0 255.255.240.0

Routing entry for 172.16.0.0/20 Known via "ospf 1", distance 110, metric 20, type intra area Last update from 192.168.1.2 on GigabitEthernet0/0, 00:00:15 ago Routing Descriptor Blocks:

* 192.168.1.2, from 192.168.1.2, 00:00:15 ago, via GigabitEthernet0/0

Route metric is 20, traffic share count is 1

Based on this output, what can be concluded about the route 172.16.0.0/20?

Trap 1: The route is a default route.

The prefix is 172.16.0.0/20, not 0.0.0.0/0.

Trap 2: The route is an external route.

The route type is intra area, not external.

Trap 3: The route is a connected route.

It is learned via OSPF, not connected.

A
The route is a default route.
Why wrong: The prefix is 172.16.0.0/20, not 0.0.0.0/0.
B
The route is an inter-area summary route.
The metric of 20 and intra-area type suggest it is a summary route from an ABR (type 3 LSA).
C
The route is an external route.
Why wrong: The route type is intra area, not external.
D
The route is a connected route.
Why wrong: It is learned via OSPF, not connected.

Question 12mediummultiple choice

A network engineer runs the following command on Router R1:

R1# show ip bgp 192.168.0.0 255.255.252.0

BGP routing table entry for 192.168.0.0/22, version 5 Paths: (1 available, best #1, table default) Advertised to update-groups: 1 Refresh Epoch 1 65001

10.1.1.1 from 10.1.1.1 (10.1.1.1)

Origin IGP, metric 0, localpref 100, valid, external, best Community: 65001:100 rx pathid: 0, tx pathid: 0x0 Aggregator: 65001, 10.1.1.1

Based on this output, what is true about this route?

Trap 1: The route is a learned route from AS 65002.

The AS path is 65001, not 65002.

Trap 2: The route is a default route.

The prefix is 192.168.0.0/22, not 0.0.0.0/0.

Trap 3: The route is suppressed.

There is no indication of suppression; the route is best.

A
The route is a summary route aggregated by 10.1.1.1.
The Aggregator field shows 65001, 10.1.1.1, indicating this route is an aggregate.
B
The route is a learned route from AS 65002.
Why wrong: The AS path is 65001, not 65002.
C
The route is a default route.
Why wrong: The prefix is 192.168.0.0/22, not 0.0.0.0/0.
D
The route is suppressed.
Why wrong: There is no indication of suppression; the route is best.

Question 13mediummultiple choice

A network engineer runs the following command on Router R1:

R1# show ip eigrp interfaces detail GigabitEthernet0/0

IP-EIGRP interfaces for process 100

Interface                    Peers  Xmit Queue   Mean   Pacing Time   Multicast    Pending

Un/Reliable SRTT Un/Reliable Flow Timer Routes Gi0/0 1 0/0 10 0/10 50 0 Hello interval: 5 sec, Hold time: 15 sec Split horizon is enabled Summary address: 10.0.0.0/8 Next xmit serial <none> Un/reliable mcasts: 0/0 Un/reliable ucasts: 0/0 Mcast exceptions: 0 CR packets: 0 ACKs suppressed: 0 Retransmissions: 0 Retry timer: 15 Hello packets sent: 100, received: 99

Based on this output, what is the purpose of the summary address configured on this interface?

Trap 1: It filters all routes in the 10.0.0.0/8 range.

Summary address advertises a summary, not filter.

Trap 2: It redistributes connected routes.

Summary address is not for redistribution.

Trap 3: It disables split horizon.

Split horizon is still enabled.

A
It filters all routes in the 10.0.0.0/8 range.
Why wrong: Summary address advertises a summary, not filter.
B
It advertises a summary route 10.0.0.0/8 to neighbors.
The summary address configuration causes R1 to advertise a summary route 10.0.0.0/8 on this interface.
C
It redistributes connected routes.
Why wrong: Summary address is not for redistribution.
D
It disables split horizon.
Why wrong: Split horizon is still enabled.

Question 14mediummultiple choice

A network engineer runs the following command on Router R1:

R1# show ip ospf database summary 172.16.0.0

OSPF Router with ID (1.1.1.1) (Process ID 1)

Summary Net Link States (Area 0)

LS age: 100 Options: (No TOS-capability, DC) LS Type: Summary Links(Network) Link State ID: 172.16.0.0 (Summary Network Number) Advertising Router: 2.2.2.2 LS Seq Number: 80000001 Checksum: 0x1234 Length: 28 Network Mask: /20 TOS: 0 Metric: 10

Based on this output, what does this LSA represent?

Trap 1: It is a router LSA from R1.

The LS Type is Summary Links, not Router Links.

Trap 2: It is an external route from ASBR.

Type 5 LSAs are external; this is Type 3.

Trap 3: It is a network LSA for the 172.16.0.0 network.

Network LSA is Type 2, not Type 3.

A
It is a router LSA from R1.
Why wrong: The LS Type is Summary Links, not Router Links.
B
It is a summary route for 172.16.0.0/20 advertised by ABR 2.2.2.2.
This Type 3 LSA advertises a summary route for 172.16.0.0/20 from ABR 2.2.2.2.
C
It is an external route from ASBR.
Why wrong: Type 5 LSAs are external; this is Type 3.
D
It is a network LSA for the 172.16.0.0 network.
Why wrong: Network LSA is Type 2, not Type 3.

Question 15hardmultiple choice

A network engineer runs the following command on Router R1:

R1# show ip route summary

IP routing table maximum-paths: 32
IP routing table has 15 routes, using 900 bytes of memory

Number of prefixes: /8: 1, /16: 2, /20: 3, /24: 9 Route types: Connected: 4, Static: 1, OSPF: 10 Route sources: OSPF: 10, Connected: 4, Static: 1

Based on this output, what is a potential issue regarding route summarization?

Trap 1: The routing table is too small.

15 routes is not large, but the issue is lack of summarization.

Trap 2: There are too many OSPF routes.

10 OSPF routes is not excessive.

Trap 3: The routing table is empty.

There are 15 routes.

A
The routing table is too small.
Why wrong: 15 routes is not large, but the issue is lack of summarization.
B
There are too many /24 prefixes, suggesting poor summarization.
Having 9 /24 prefixes indicates that more specific routes are present, and summarization could reduce the table size.
C
There are too many OSPF routes.
Why wrong: 10 OSPF routes is not excessive.
D
The routing table is empty.
Why wrong: There are 15 routes.

Question 16hardmultiple choice

A network engineer runs the following command on Router R1:

R1# show ip bgp neighbors 10.1.1.1 advertised-routes

BGP table version is 10, local router ID is 1.1.1.1 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter, x best-external, a additional-path, c RIB-compressed, Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path *> 10.0.0.0/8 0.0.0.0 0 32768 i *> 10.1.0.0/16 0.0.0.0 0 32768 i *> 10.1.1.0/24 0.0.0.0 0 32768 i *> 10.1.2.0/24 0.0.0.0 0 32768 i

Based on this output, what is a problem with the BGP advertisements?

Trap 1: The router is not advertising any routes.

It is advertising multiple routes.

Trap 2: The router is only advertising the summary route.

It also advertises more specific routes.

Trap 3: The router is using incorrect next-hop.

Next-hop 0.0.0.0 is normal for locally originated routes.

A
The router is not advertising any routes.
Why wrong: It is advertising multiple routes.
B
The router is advertising overlapping prefixes, including both summary and specific routes.
The presence of 10.0.0.0/8 and more specific prefixes like 10.1.1.0/24 indicates overlapping advertisements, which is inefficient.
C
The router is only advertising the summary route.
Why wrong: It also advertises more specific routes.
D
The router is using incorrect next-hop.
Why wrong: Next-hop 0.0.0.0 is normal for locally originated routes.

Question 17hardmultiple choice

A network engineer runs the following command on Router R1:

R1# show ip route 10.0.0.0 255.255.252.0 longer-prefixes

Routing entry for 10.0.0.0/22 Known via "eigrp 100", distance 90, metric 2172416, type internal Last update from 192.168.1.2 on GigabitEthernet0/0, 00:00:10 ago Routing Descriptor Blocks:

* 192.168.1.2, from 192.168.1.2, 00:00:10 ago, via GigabitEthernet0/0

Route metric is 2172416, traffic share count is 1

Routing entry for 10.0.1.0/24 Known via "eigrp 100", distance 90, metric 2812416, type internal Last update from 192.168.1.2 on GigabitEthernet0/0, 00:00:10 ago Routing Descriptor Blocks:

* 192.168.1.2, from 192.168.1.2, 00:00:10 ago, via GigabitEthernet0/0

Route metric is 2812416, traffic share count is 1

Based on this output, what is the effect of the summary route 10.0.0.0/22?

Trap 1: The summary route is working correctly and suppressing all…

A more specific route (10.0.1.0/24) is still present.

Trap 2: The summary route has a better metric than the specific route.

The metric is lower (2172416 vs 2812416), but the issue is suppression.

Trap 3: The summary route is not installed in the routing table.

It is installed.

A
The summary route is working correctly and suppressing all specifics.
Why wrong: A more specific route (10.0.1.0/24) is still present.
B
The summary route is not suppressing the more specific route 10.0.1.0/24.
Both the summary and a more specific route are in the table, indicating the summary is not suppressing specifics.
C
The summary route has a better metric than the specific route.
Why wrong: The metric is lower (2172416 vs 2812416), but the issue is suppression.
D
The summary route is not installed in the routing table.
Why wrong: It is installed.

Question 18hardmultiple choice

A network engineer runs the following command on Router R1:

R1# show ip eigrp topology summary

IP-EIGRP Topology Table for AS(100)/ID(1.1.1.1) Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - reply Status, s - sia Status

P 10.0.0.0/8, 1 successors, FD is 2812416, serno 10 via Summary (2812416/0), Null0 P 10.0.0.0/24, 1 successors, FD is 2172416, serno 5 via 192.168.1.2 (2172416/2812416), GigabitEthernet0/0 P 10.0.1.0/24, 1 successors, FD is 2172416, serno 6 via 192.168.1.2 (2172416/2812416), GigabitEthernet0/0

Based on this output, what is the purpose of the route 10.0.0.0/8 via Null0?

Trap 1: It is a default route for unknown destinations.

It is a summary route, not a default route.

Trap 2: It is a route learned from a neighbor.

It is via Summary, not from a neighbor.

Trap 3: It is a connected route.

It is not connected; it is a summary route.

A
It is a default route for unknown destinations.
Why wrong: It is a summary route, not a default route.
B
It is a discard route to prevent routing loops.
The Null0 interface indicates this is a discard route, commonly used with summarization to avoid loops.
C
It is a route learned from a neighbor.
Why wrong: It is via Summary, not from a neighbor.
D
It is a connected route.
Why wrong: It is not connected; it is a summary route.

Question 19mediummultiple choice

Consider the following partial EIGRP configuration on router R1:

router eigrp 100
 network 10.0.0.0
 network 192.168.1.0

summary-address 10.0.0.0 255.255.255.0 5

What is the effect of the 'summary-address 10.0.0.0 255.255.255.0 5' command?

Trap 1: It creates a summary route 10.0.0.0/24 and sets the metric to 5.

Incorrect. The value 5 is the administrative distance, not the metric.

Trap 2: It creates a summary route 10.0.0.0/24 and suppresses more specific…

Incorrect. The value does not affect metric suppression.

Trap 3: It creates a summary route 10.0.0.0/24 with a tag of 5.

Incorrect. The value is administrative distance, not a tag.

A
It creates a summary route 10.0.0.0/24 with an administrative distance of 5, advertised out all EIGRP-enabled interfaces.
Correct. The summary-address command creates a summary route and the optional distance value sets the administrative distance for that summary.
B
It creates a summary route 10.0.0.0/24 and sets the metric to 5.
Why wrong: Incorrect. The value 5 is the administrative distance, not the metric.
C
It creates a summary route 10.0.0.0/24 and suppresses more specific routes with a metric of 5.
Why wrong: Incorrect. The value does not affect metric suppression.
D
It creates a summary route 10.0.0.0/24 with a tag of 5.
Why wrong: Incorrect. The value is administrative distance, not a tag.

Question 20mediummultiple choice

Given the following OSPF configuration on router R2:

router ospf 1
 network 10.0.0.0 0.255.255.255 area 0
 area 0 range 10.0.0.0 255.255.252.0

Which statement is true about this configuration?

Trap 1: Router R2 will summarize routes from area 0 into other areas.

Incorrect. The area range command summarizes routes into the specified area, not from it.

Trap 2: Router R2 will create a static route for 10.0.0.0/22.

Incorrect. The area range command does not create static routes.

Trap 3: Router R2 will filter all routes not within 10.0.0.0/22.

Incorrect. The area range command summarizes, not filters.

A
Router R2 will advertise a summary route 10.0.0.0/22 into area 0 from other areas.
Correct. The area range command on an ABR summarizes routes from other areas into area 0.
B
Router R2 will summarize routes from area 0 into other areas.
Why wrong: Incorrect. The area range command summarizes routes into the specified area, not from it.
C
Router R2 will create a static route for 10.0.0.0/22.
Why wrong: Incorrect. The area range command does not create static routes.
D
Router R2 will filter all routes not within 10.0.0.0/22.
Why wrong: Incorrect. The area range command summarizes, not filters.