CCNA IP Routing Practice Test 10 — 15 Questions

Question 1

Two OSPF routers connected over Ethernet fail to become neighbors. Their interfaces are up/up and in the same IPv4 subnet. One router uses area 0 and the other uses area 1 on the connecting interfaces. What is the most likely cause?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Mismatched OSPF areas on the shared link. OSPF neighbors on the same link must agree on key parameters, including the area assigned to that interface. A mismatch prevents the adjacency from forming.

Answer

Mismatched OSPF process IDs

Answer

Missing default routes

Answer

Different router IDs

Question 2

A static route is configured as 198.51.100.0/24 via 192.0.2.9, but the connected network to the next hop goes down. What happens to the static route in the routing table?

Accepted Answer

It is removed because the recursive next hop is no longer reachable.. If the outgoing interface or connected path to the next hop becomes unreachable, the router cannot resolve the recursive next hop and the route is removed from the table.

Answer

It remains permanently because static routes never disappear.

Answer

It changes automatically into a default route.

Answer

It becomes an OSPF external route.

Question 3

Which two statements about OSPF neighbor requirements on a shared Ethernet segment are correct? (Choose two.)

Accepted Answer

They must be in the same OSPF area on that link.. Neighbors must agree on key parameters such as area ID and subnet, and they exchange Hello packets on the segment.

Answer

They must have identical router IDs.

Answer

They must use the same process ID number on both routers.

Question 4

Two OSPF routers connected on an Ethernet link remain in the INIT state. Which issue is the most likely cause?

Accepted Answer

The routers cannot exchange Hellos bidirectionally on the segment. INIT means a router is seeing Hellos from its neighbor but does not see its own router ID in the neighbor field of received Hellos. A common cause is one-way communication or a mismatched multicast/adjacency problem, often at Layer 2.

Answer

The routers have identical router IDs

Answer

The routers have already reached FULL and are waiting to install routes

Answer

The routers are using the same OSPF process ID

Question 5

A router learns 203.0.113.0/24 through OSPF and 203.0.113.0/25 through a static route. Which route is used for traffic destined to 203.0.113.10?

Accepted Answer

The static /25 route. Routers prefer the most specific matching route first. The /25 route is more specific than the /24 and includes 203.0.113.10.

Answer

The OSPF /24 route

Answer

Both routes equally

Answer

Neither route because the prefixes overlap

Question 6

Which OSPF network type on Ethernet performs a DR and BDR election by default?

Accepted Answer

Broadcast. Broadcast multiaccess networks such as Ethernet elect a DR and BDR by default.

Answer

Point-to-point

Answer

Point-to-multipoint nonbroadcast

Answer

Loopback

Question 7

A router shows the following route:

O    10.10.40.0/24 [110/20] via 192.0.2.2, 00:00:12, GigabitEthernet0/0

What does the value 110 represent?

Accepted Answer

The administrative distance of OSPF. In Cisco route output, the value in brackets is [administrative distance/metric].

Answer

The OSPF cost to the destination

Answer

The number of hops to the destination

Answer

The route age in seconds

Question 8

A router shows the following routing table entries for the same destination:

O    10.10.50.0/24 [110/20] via 192.168.12.2, GigabitEthernet0/0
D    10.10.50.0/24 [90/30720] via 192.168.13.2, GigabitEthernet0/1

Which route will become the active route in the routing table?

Accepted Answer

The EIGRP route, because its administrative distance is lower. The EIGRP route becomes active because the router compares administrative distance first when the same destination is learned from different routing protocols. This is one of the most common Cisco exam traps: candidates compare the OSPF metric value of 20 to the EIGRP metric value and assume the smaller number must win. That is not how route selection works across different protocols. OSPF metrics and EIGRP metrics are calculated differently, so the router does not compare them directly. Instead it checks administrative distance. EIGRP internal routes default to 90, while OSPF routes default to 110. Since 90 is lower than 110, the EIGRP route is trusted more and is installed as the active path.

Answer

The OSPF route, because its metric is lower

Answer

Both routes, because the prefixes are identical

Answer

Neither route, because the metrics use different scales

Question 9

A router interface is configured for OSPF, but neighbors do not form. The engineer checks the interface and sees Hello 10 and Dead 40. The neighbor on the same segment uses Hello 30 and Dead 120.

What is the most likely cause of the OSPF adjacency failure?

Accepted Answer

OSPF timers do not match. The adjacency fails because the OSPF hello and dead timers do not match. OSPF neighbors on the same segment must agree on several key parameters before they accept each other as neighbors, and the timer settings are one of those required matches. In plain terms, each router is expecting to hear OSPF hellos at one rhythm, but the other side is speaking at a different rhythm, so the relationship never becomes valid. This is different from cost, which matters later during path selection after neighbors are already exchanging information. The timer mismatch is a classic CCNA troubleshooting point because the interfaces can be up and IP connectivity can even appear normal while the OSPF adjacency still fails.

Answer

Router IDs are identical

Answer

The interface cost is too low

Answer

The subnet mask is invalid because it is a transit link

Question 10

A packet destined for 10.1.1.130 arrives at the router. Based on the routing table, which route will be used?

Accepted Answer

The static route to 10.1.1.128/25. Routers do not choose the route with the lowest administrative distance first when several routes match a destination. They begin with the most specific matching prefix. In practical terms, the router looks for the narrowest route that still contains the destination address. The packet is going to 10.1.1.130. That address fits inside 10.1.1.128/25, and it also fits inside 10.1.1.0/24 and 10.1.0.0/16. But /25 is the most specific of those matches, so the router uses it.

Only after determining that two routes have the same prefix length would the router consider administrative distance and metric. The default route is ignored because more specific matches exist.

Answer

The default route

Answer

The OSPF route to 10.1.1.0/24

Answer

The OSPF route to 10.1.0.0/16

Question 11

R1 has the following static route configured:

ip route 0.0.0.0 0.0.0.0 203.0.113.1

What does this route accomplish?

Accepted Answer

It creates a default route used when no more specific route exists.. This command creates a default static route. In everyday terms, it tells the router, “If you do not know a more specific way to reach a destination, send the traffic to 203.0.113.1.” That next-hop address usually points toward an upstream router or ISP edge. The command does not describe one specific remote network; it represents every destination not otherwise matched by a more specific entry.

At the routing-table level, `0.0.0.0 0.0.0.0` is the broadest possible IPv4 prefix. Because it matches everything, it is used only when nothing more specific exists.

Answer

It blocks unknown destinations from leaving the router.

Answer

It creates a host route to 203.0.113.1 only.

Answer

It advertises all connected routes into OSPF.

Question 12

A network engineer enters the following configuration on R1 and R2, but R1 cannot form an OSPF adjacency with R2 on interface GigabitEthernet0/0.

R1# show running-config interface GigabitEthernet0/0
interface GigabitEthernet0/0
 ip address 10.0.0.1 255.255.255.0
 ip ospf hello-interval 10
 ip ospf dead-interval 40
 ip ospf 1 area 0
!
R2# show running-config interface GigabitEthernet0/0
interface GigabitEthernet0/0
 ip address 10.0.0.2 255.255.255.0
 ip ospf hello-interval 5
 ip ospf dead-interval 20
 ip ospf 1 area 0

What is the most likely cause of the failure?

Accepted Answer

The OSPF timers on the interface do not match.. The routers must agree on hello and dead timers to establish an OSPF adjacency. R1 uses hello=10 and dead=40, while R2 uses hello=5 and dead=20; this mismatch prevents the neighbor relationship. Although both routers share the same area (0) and subnet mask, and OSPF process IDs are locally significant (no match required), the timer difference is the root cause.

Answer

The routers are in different OSPF areas.

Answer

The subnet mask prevents multicast OSPF packets from being exchanged.

Answer

The OSPF process IDs do not match on the two routers.

Question 13

A router has these routes installed. Which path will be chosen for traffic to 172.16.10.200?

Accepted Answer

S 172.16.10.128/25 via 10.1.1.6. When multiple routes could match a destination, the router first uses longest-prefix match. In plain language, it chooses the route that describes the destination most specifically, not simply the one from the protocol with the lowest metric somewhere else in the table. For 172.16.10.200, the key is to determine which listed prefix actually contains that address and is the narrowest valid match.

If a /25 and a /24 both match, the /25 wins because it is more specific. If the destination does not fit inside the smaller subnet, then the broader route is used instead. That is the entire skill being tested here: careful evaluation of the prefix boundaries before thinking about anything else. Once you recognize the address falls within the upper half of the /24, the more specific route becomes obvious.

Answer

O 172.16.10.0/24 via 10.1.1.2

Answer

O 172.16.0.0/16 via 10.1.1.10

Answer

S* 0.0.0.0/0 via 203.0.113.1

Question 14

Which two statements accurately describe longest-prefix match in routing?

Accepted Answer

The most specific matching route is preferred over broader matching routes.. Longest-prefix match means a router prefers the most specific route that matches the destination. In plain language, if several entries could apply to a packet, the router chooses the one that narrows the destination range most precisely. This is why a /25 can beat a /24, and a /24 can beat a /16, even if all three technically contain the same destination address.

The common mistake is to assume the router always begins with protocol trust or metric. Those factors matter, but only after the router has determined which matching routes share the same prefix length.

Answer

A default route is preferred over a matching /24 because it is simpler.

Answer

Routers ignore subnet masks and choose only by administrative distance.

Answer

A /16 is always more specific than a /24.

Question 15

Why does a passive interface in OSPF still matter even though it does not send hello packets?

Accepted Answer

The connected network can still be advertised into OSPF through other active adjacencies. A passive interface still matters because the connected network can still be advertised into OSPF even though the interface itself does not form neighbor relationships. In plain language, the router is saying, “This network is mine, and I want others to know about it, but I do not want to speak OSPF directly on this interface.” That is useful on user-facing or stub-like interfaces where no OSPF neighbor should exist.

This distinction is important because some engineers assume passive means “ignored entirely.” It does not. The connected network can still appear in routing updates sent through real neighbors on other interfaces. What changes is neighbor formation on the passive interface itself.

Answer

The passive interface automatically becomes the OSPF router ID

Answer

The passive interface disables all OSPF operation on the router

Answer

The passive interface converts OSPF into EIGRP on that link