Route Summarization

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?

Question 3hardmultiple 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?

Question 4mediummultiple 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?

Question 5hardmultiple choice

Review the full subnetting walkthrough →

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?

Question 6mediummultiple 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?

Question 7hardmultiple 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?

Question 8mediummultiple 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?

Question 9mediummultiple 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?

Question 10hardmultiple 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?

Question 11mediummultiple 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?

Question 12mediummultiple 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?

Question 13mediummultiple 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?

Question 14mediummultiple 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?

Question 15mediummultiple 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?

Question 16hardmultiple 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?

Question 17hardmultiple 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?

Question 18hardmultiple 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?

Question 19hardmultiple 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?

Question 20mediummultiple 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?

Question 21mediummultiple 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?

Question 22mediummultiple choice

Examine this BGP configuration on router R3:

router bgp 65001
 neighbor 10.1.1.1 remote-as 65002

address-family ipv4

network 192.168.0.0 mask 255.255.252.0

aggregate-address 192.168.0.0 255.255.252.0 summary-only

What is the effect of the 'aggregate-address' command with the 'summary-only' keyword?

Question 23mediummultiple choice

Review the following OSPF configuration on router R4:

router ospf 1
 network 10.0.0.0 0.255.255.255 area 0
 area 1 range 10.0.0.0 255.255.255.0

What is missing or incorrect in this configuration for proper route summarization?

Question 24mediummultiple choice

Consider this EIGRP configuration on router R5:

interface GigabitEthernet0/0
 ip summary-address eigrp 100 10.10.0.0 255.255.0.0 5

router eigrp 100
 network 10.0.0.0

What is the effect of the 'ip summary-address eigrp' command on interface GigabitEthernet0/0?

Question 25mediummultiple choice

Given this partial configuration on router R6:

router bgp 65000
 neighbor 192.168.1.1 remote-as 65001

address-family ipv4

network 172.16.0.0 mask 255.255.0.0

aggregate-address 172.16.0.0 255.255.0.0

What is missing if the administrator wants to ensure that only the aggregate route is advertised to neighbor 192.168.1.1?

Question 26easymultiple choice

In OSPF, what is the default metric for a Type 3 summary LSA generated by an ABR using the 'area range' command?

Question 27easymultiple choice

In EIGRP, what is the default administrative distance of a summary route created with the 'ip summary-address eigrp' command?

Question 28mediummultiple choice

Which of the following best describes the behavior of BGP when an 'aggregate-address' command is used without the 'summary-only' keyword?

Question 29mediummulti select

Which TWO commands can be used to verify route summarization on a Cisco router running OSPF? (Choose TWO.)

Question 30hardmulti select

Which TWO statements about route summarization in EIGRP are true? (Choose TWO.)

Question 31mediummulti select

Full Practice Test →All Objectives

Which TWO configuration steps are required to implement manual route summarization in OSPF on an ABR? (Choose TWO.)

More Route Summarization questions available in the full practice test.

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All 300-410 Objectives

Objective 109.0

Route Summarization

300-410 Practice Questions

300-410 Route Summarization — Practice Questions

30 questions from this objective

Question 2mediummultiple choice

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?

Question 3hardmultiple 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?

Question 4mediummultiple 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?

Question 5hardmultiple choice

Review the full subnetting walkthrough →

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?

Question 6mediummultiple 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?

Question 7hardmultiple 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?

Question 8mediummultiple 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?

Question 9mediummultiple 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?

Question 10hardmultiple 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?

Question 11mediummultiple choice

A network engineer runs the following command on Router R1:

R1# show ip eigrp topology 10.0.0.0 255.255.252.0

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

Question 12mediummultiple 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?

Question 13mediummultiple 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?

Question 14mediummultiple 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

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

Question 15mediummultiple 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)

Based on this output, what does this LSA represent?

Question 16hardmultiple 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?

Question 17hardmultiple choice

A network engineer runs the following command on Router R1:

R1# show ip bgp neighbors 10.1.1.1 advertised-routes

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?

Question 18hardmultiple 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?

Question 19hardmultiple 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

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

Question 20mediummultiple 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?

Question 21mediummultiple 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?

Question 22mediummultiple choice

Examine this BGP configuration on router R3:

router bgp 65001
 neighbor 10.1.1.1 remote-as 65002

address-family ipv4

network 192.168.0.0 mask 255.255.252.0

aggregate-address 192.168.0.0 255.255.252.0 summary-only

What is the effect of the 'aggregate-address' command with the 'summary-only' keyword?

Question 23mediummultiple choice

Review the following OSPF configuration on router R4:

router ospf 1
 network 10.0.0.0 0.255.255.255 area 0
 area 1 range 10.0.0.0 255.255.255.0

What is missing or incorrect in this configuration for proper route summarization?

Question 24mediummultiple choice

Consider this EIGRP configuration on router R5:

interface GigabitEthernet0/0
 ip summary-address eigrp 100 10.10.0.0 255.255.0.0 5

router eigrp 100
 network 10.0.0.0

What is the effect of the 'ip summary-address eigrp' command on interface GigabitEthernet0/0?

Question 25mediummultiple choice

Given this partial configuration on router R6:

router bgp 65000
 neighbor 192.168.1.1 remote-as 65001

address-family ipv4

network 172.16.0.0 mask 255.255.0.0

aggregate-address 172.16.0.0 255.255.0.0

What is missing if the administrator wants to ensure that only the aggregate route is advertised to neighbor 192.168.1.1?

Question 26easymultiple choice

In OSPF, what is the default metric for a Type 3 summary LSA generated by an ABR using the 'area range' command?

Question 27easymultiple choice

In EIGRP, what is the default administrative distance of a summary route created with the 'ip summary-address eigrp' command?

Question 28mediummultiple choice

Which of the following best describes the behavior of BGP when an 'aggregate-address' command is used without the 'summary-only' keyword?

Question 29mediummulti select

Which TWO commands can be used to verify route summarization on a Cisco router running OSPF? (Choose TWO.)

Question 30hardmulti select

Which TWO statements about route summarization in EIGRP are true? (Choose TWO.)

Question 31mediummulti select