CCNA IP Routing Practice Test 15 — 15 Questions

Question 1

A router has a static route to 10.30.5.128/25, an OSPF route to 10.30.5.0/24, and a default route 0.0.0.0/0 in its routing table. Which route will the router use for destination 10.30.5.130?

Accepted Answer

The static route to 10.30.5.128/25. The router selects the route with the longest prefix match between the destination IP and the prefixes in the routing table. 10.30.5.130 matches both 10.30.5.0/24 (prefix length 24) and 10.30.5.128/25 (prefix length 25); the /25 is more specific and wins. Option D is wrong because 10.30.5.130 falls within the subnet range of 10.30.5.128/25 (hosts .129–.254), so a valid route does exist.

Answer

The OSPF route to 10.30.5.0/24

Answer

The default route

Answer

No route, because the destination is outside all prefixes shown.

Question 2

Based on the exhibit, which route will be used for destination 192.168.10.130?

Accepted Answer

The static route to 192.168.10.128/25. The route used will be the one with the longest matching prefix. In practical terms, 192.168.10.130 matches both the /24 and the /25 prefixes shown, but the /25 is more specific. Because longest-prefix match comes first, the router uses the /25 route even though other matching routes are present.

This is a clean route-table interpretation question that is very close to real exam reasoning.

Answer

The OSPF route to 192.168.10.0/24

Answer

The default route

Answer

No route at all

Question 3

Why does traffic to 172.31.80.10 use the RIP route (172.31.80.0/24) instead of the static route (172.31.0.0/16)?

Accepted Answer

Because the RIP /24 route is more specific than the static /16 route.. Traffic uses the RIP route because the static route is less specific than the RIP route. In practical terms, longest-prefix match is always evaluated first. Even though the static route is manually configured, the more specific RIP prefix wins because it describes the destination more precisely.

This is a strong route-selection item because it tests whether you can prioritize specificity ahead of route source preference.

Answer

Because RIP always overrides static routing.

Answer

Because static routes cannot be used for private IPv4 space.

Answer

Because the static route is automatically removed whenever RIP is enabled.

Question 4

A router has a static route and a RIP route for the same destination prefix. What is the primary reason the static route is preferred over the RIP route?

Accepted Answer

Because the static route has a lower administrative distance for the same prefix.. The static route is preferred because both routes describe the same destination prefix and the static route has the lower administrative distance. In practical terms, longest-prefix match does not break the tie because the prefixes are equal. The router then compares source trust, and static routing wins over RIP by default.

This is a core route-selection concept and a very exam-relevant comparison.

Answer

Because RIP can never be installed when static routing is configured anywhere.

Answer

Because RIP is valid only for host routes.

Answer

Because static routes are always more specific than RIP routes.

Question 5

R1 and R2 are connected via a shared Ethernet segment. Both routers are configured in OSPF area 0 and are on the same IP subnet. OSPF authentication is enabled on both interfaces, but the adjacency is not forming. What is the most likely reason?

Accepted Answer

The OSPF authentication key does not match on the two routers.. The most likely reason is an OSPF authentication mismatch. In practical terms, both routers are on the same IP subnet and in the same area, but they are not using the same authentication key on the shared link. OSPF neighbors must agree on key authentication parameters before they will trust each other enough to form an adjacency.

This is a classic CCNA troubleshooting pattern because the configuration looks almost correct until you compare the security settings carefully.

Answer

The routers must use different OSPF areas to become neighbors.

Answer

OSPF message-digest authentication can be used only on serial links.

Answer

The routers must remove IP addressing before OSPF can form.

Question 6

When two routes to the same destination are learned by OSPF from different paths, what criterion does OSPF use to select the best path?

Accepted Answer

Lowest OSPF cost. Within OSPF, the router compares the total path cost to the destination. Lower cost is preferred. Administrative distance is used when comparing routes from different routing sources, not between two OSPF paths.

Answer

Lowest administrative distance

Answer

Highest bandwidth of the first hop only

Answer

Lowest next-hop IP address

Question 7

An OSPF-enabled router R1 fails to advertise the 192.168.50.0/24 network to neighbor R2, even though the neighbor relationship is up. Which misconfiguration on R1 would cause this?

Accepted Answer

The wildcard network statement does not match 192.168.50.0/24. If the network statement on R1 does not match the interface connected to 192.168.50.0/24, OSPF will not enable on that interface and the subnet will not be advertised. The route stays absent from neighbors despite OSPF running elsewhere.

Answer

The OSPF process must be process ID 50 to advertise 192.168.50.0/24

Answer

OSPF cannot advertise a directly connected LAN

Answer

R2 needs a default route before learning intra-area routes

Question 8

Exhibit: R1 has the static route 'ip route 0.0.0.0 0.0.0.0 192.0.2.2 200' and also learns a default route from OSPF. Which default route will be installed while the OSPF route is present?

Accepted Answer

The OSPF default route. The OSPF external default route wins because its administrative distance is 110, which is lower than the floating static route's distance of 200. The static route is intentionally given a higher AD so it is used only as a backup.

Answer

The static default route

Answer

Both default routes with per-packet load balancing

Answer

Neither route because floating statics suppress dynamic defaults

Question 9

A branch router learns a route to 10.20.30.0/24 from OSPF with metric 30 and also has a static route to the same prefix with an administrative distance of 5. Which route will appear in the routing table?

Accepted Answer

The static route because its administrative distance is lower. The router installs the static route because administrative distance is compared before metric when two different routing sources advertise the same prefix. OSPF metric matters only against other OSPF choices, not against a lower-AD static route.

Answer

The OSPF route because metric 30 is lower than the static route metric

Answer

Both routes with equal preference because they point to the same prefix

Answer

Neither route until the router performs a full SPF recalculation

Question 10

R1 and R2 are directly connected via Ethernet on interface G0/0. Both interfaces are in the same subnet and configured for OSPF area 0. After enabling OSPF, R1's G0/0 is stuck in the INIT state in the OSPF neighbor table. What is the most likely cause?

Accepted Answer

Hello and dead timer mismatch. Being stuck in the INIT state means R1 has received Hello packets from R2 but has not transitioned to the 2-WAY state. This most often occurs when critical OSPF parameters like the hello and dead timers do not match. An MTU mismatch, while problematic, would cause the adjacency to fail during database exchange (Exstart/Exchange), not during initial neighbor formation. Missing router IDs are not a real issue because routers auto-generate them, and a duplicate static route to the connected subnet would not affect OSPF neighbor discovery.

Answer

MTU mismatch

Answer

Missing router ID on both routers

Answer

A duplicate static route to 10.1.12.0/30

Question 11

R1 and R2 are directly connected. Their interfaces are up/up and belong to the same subnet. R1's OSPF configuration places the interface in area 0, while R2's interface is in area 1. R1 does not show R2 as an OSPF neighbor. What is the most likely cause?

Accepted Answer

The area IDs do not match. OSPF neighbors on the same link must agree on the area ID. Here, one side is in area 0 and the other is in area 1, so adjacency never forms even though the interfaces are up and in the same subnet.

Answer

R1 must use a loopback as the router ID

Answer

The subnet mask is too small for OSPF to work

Answer

R2 should be configured as the DR manually

Question 12

Exhibit: R1 has a default route pointing to 10.1.1.2. Users lose internet access when that next hop fails, even though a floating static backup exists. Why is the backup not installed?

Accepted Answer

The primary static route remains installed because there is no tracking to remove it. A floating static route is used only when the primary route disappears from the routing table. If the primary interface stays up and the next hop becomes unreachable beyond that segment, the route can remain installed unless tracking or another detection mechanism removes it.

Answer

The backup route has a higher administrative distance and therefore is never considered

Answer

Floating statics work only with dynamic routing protocols

Answer

The backup route must use the same next hop as the primary route

Question 13

A router learns 172.16.40.0/24 from OSPF with AD 110 and metric 20. It also learns the same prefix from EIGRP with AD 90 and feasible distance 30720. Which route is installed?

Accepted Answer

The EIGRP route because its administrative distance is lower. When the same prefix is learned from different routing protocols, the router compares administrative distance first. EIGRP internal routes have AD 90, which beats OSPF AD 110, so the EIGRP path goes into the table.

Answer

The OSPF route because metric 20 is lower than 30720

Answer

Both routes because ECMP is automatic across different protocols

Answer

Neither route until one is redistributed into the other protocol

Question 14

Exhibit: R3 learns 10.50.0.0/16 by OSPF through two equal-cost paths. What will R3 do by default?

Accepted Answer

Install both routes and load balance. When OSPF has equal-cost routes to the same destination, the router installs multiple paths and can load balance across them, assuming the platform supports the default maximum-paths value.

Answer

Choose the route from the neighbor with the highest router ID only

Answer

Install only one route because OSPF does not support ECMP

Answer

Prefer the path with the lower next-hop IP address

Question 15

Exhibit: A router has the following routes in its routing table:
- OSPF: 10.1.1.0/24
- Static: 10.1.1.128/25
- Default: 0.0.0.0/0

A packet is destined for 10.1.1.130. Which route does the router use?

Accepted Answer

The static 10.1.1.128/25 route. Routers use longest-prefix match before they think about metrics. The /25 route for 10.1.1.128/25 is more specific than the /24 or the default route, so traffic for 10.1.1.130 follows that path.

Answer

The OSPF 10.1.1.0/24 route

Answer

The default route

Answer

The router load-balances across all three