CCNA Practice Test 38 — 15 Questions

Question 1

Refer to the exhibit. An engineer configured PortFast on interface GigabitEthernet0/1, which connects to a server that does not participate in spanning tree. However, the port remains in the listening state for the full forward delay period before transitioning to forwarding. The engineer issues the show spanning-tree vlan 10 detail command. Based on the output, what is the most likely cause?

Accepted Answer

The port is configured as a trunk, so PortFast is not active.. The exhibit shows that GigabitEthernet0/1 is in ‘listening’ state with a forward delay timer of 12 seconds, and the lines ‘Edge port: no (default) portfast: no (default)’ indicate that PortFast is disabled. PortFast only takes effect on access ports; since the port is configured as a trunk (implied by the disconnected state of PortFast despite the engineer’s configuration), it does not skip listening/learning. The port is not in err-disabled state (no BPDU Guard block), and no BPDUs have been received (BPDU: received 0), ruling out other options.

Answer

BPDU Guard is enabled on the port, causing it to block.

Answer

The forward delay timer is set too high, and PortFast cannot override it.

Answer

The server is sending BPDUs, causing the port to lose its PortFast state.

Question 2

Which command correctly configures an IPv6 default route using next-hop address 2001:db8:1::1?

Accepted Answer

ipv6 route ::/0 2001:db8:1::1. The correct IPv6 default route uses the prefix ::/0 with the command 'ipv6 route ::/0'. Option B is wrong because 'ip route' is used for IPv4 routes, not IPv6. Option C uses 'ipv6 default-route', which is not a valid Cisco IOS command. Option D sets the management default gateway for IPv4 only and does not insert a route into the IPv6 routing table.

Answer

ip route :: 2001:db8:1::1

Answer

ipv6 default-route 2001:db8:1::1

Answer

ip default-gateway 2001:db8:1::1

Question 3

R1 cannot reach host 10.3.3.1 on R3. The technician checks routing: R1 has a route to 10.3.3.0/24 via next-hop 10.1.1.2 (R2). R2 has a route to 10.3.3.0/24 via next-hop 10.2.2.2 (R3). A ping from R1 to 10.3.3.1 times out. A ping from R2 to 10.3.3.1 succeeds. What should the technician do next?

Accepted Answer

Check whether an inbound ACL on R3 is blocking packets with R1’s source IP address.. Because R2 can successfully ping R3, we know that R3 is reachable, the path from R2 to R3 is functional, OSPF (or whatever IGP) is working between them, and R3 has a route back to R2's subnet. The failure is isolated to traffic sourced from R1. This strongly suggests a filtering issue that specifically denies R1's source IP address. Checking for an inbound ACL on R3’s receiving interface is the logical next step at the transport/application layer; it directly tests the hypothesis that R3 is receiving R1’s pings but discarding them due to a security policy. It avoids unnecessary investigation of routing or link-layer problems that have already been ruled out.

Answer

Verify that R3 has a route back to R1’s subnet.

Answer

Verify the OSPF neighbor adjacency between R2 and R3.

Answer

Test for an MTU mismatch along the path from R1 to R3.

Question 4

A router learns 10.10.10.0/24 from OSPF and EIGRP at the same time. OSPF reports a metric of 20, and EIGRP reports a metric of 30720. Which route is installed in the routing table by default?

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 use AD 90, while OSPF uses AD 110, so the EIGRP route is preferred.

Answer

The OSPF route, because 20 is lower than 30720

Answer

Both routes, because they point to the same prefix

Answer

Neither route, because the metrics are not comparable

Question 5

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 6

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 7

Based on the exhibit, why is the static route not being used for 172.18.9.10?

Accepted Answer

Because the connected /24 route is more specific than the static /16 route.. The static route is not being used because the connected route is the more specific match. In practical terms, route selection starts with prefix specificity. The static route covers a broad /16, but the destination 172.18.9.10 also falls inside a connected /24. The /24 wins because it is more specific.

This is a classic routing interpretation question because it tests whether you apply longest-prefix logic before thinking about route source preference.

Answer

Because static routes are never used when a connected network exists anywhere in the table.

Answer

Because connected routes always have administrative distance 255.

Answer

Because static routes work only for default routing.

Question 8

Refer to the exhibit. A network engineer is verifying OSPF routing on R1. All routers in the topology are expected to reside in OSPF area 0, and the network 172.16.0.0/16 should be advertised from R2 within the same area. The engineer issues the show ip route 172.16.0.0 command on R1 and sees the output in the exhibit. The engineer expected to see an intra-area route (O) instead of an inter-area route (O IA). What is the most likely cause of this discrepancy?

Accepted Answer

The destination network 172.16.0.0/16 is located in a different OSPF area.. The exhibit explicitly lists the route type as 'inter area' for 172.16.0.0/16. In OSPF, an inter-area (IA) route means the destination network resides in a different OSPF area than the local router. Since all routers are expected to be in area 0, the presence of an IA route indicates the 172.16.0.0/16 network is actually located in a different area, causing the ABR to generate a Type-3 summary LSA.

Answer

R1 has a mismatched OSPF process ID compared to the ABR.

Answer

The network type on GigabitEthernet0/0 is configured as non-broadcast, preventing full adjacency.

Answer

The metric for the route is too high, causing OSPF to treat it as an inter-area route.

Question 9

A network engineer notices that an OSPF adjacency between R1 and R2 is flapping between FULL and DOWN state every 40 seconds. The dead interval on both routers is configured as 40 seconds. The hello interval on R1 is 10 seconds, and on R2 it is 30 seconds. What is the most likely cause?

Accepted Answer

Mismatched hello intervals cause the dead timer on R1 to expire before receiving a hello from R2, tearing down the adjacency.. The mismatched hello intervals cause the dead timer on R1 to expire before receiving a hello from R2. R1 sends hellos every 10 seconds and expects to hear from R2 at least once every 40 seconds (dead interval). R2, however, only sends hellos every 30 seconds. Due to timing jitter and processing delays, R1's dead timer occasionally expires just before R2's hello arrives, leading to the adjacency being torn down. After the adjacency drops, OSPF attempts to re-establish it, resulting in a cyclical FULL-DOWN pattern every 40 seconds. The other options are real OSPF issues but do not produce this specific timing: duplicate router IDs would cause persistent instability without a regular interval; an authentication mismatch would prevent the adjacency from forming at all; a network type mismatch might cause DR/BDR election problems but would not flap with precise dead-interval regularity.

Answer

Duplicate OSPF router IDs are causing the adjacency to reset each time the mismatched routers see each other's LSAs.

Answer

A network type mismatch between broadcast and point-to-point is causing periodic DR/BDR elections that reset the adjacency.

Answer

An OSPF authentication mismatch is causing periodic rejection of hello packets on one router.

Question 10

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 11

Refer to the exhibit. A network engineer is troubleshooting connectivity to server 10.10.10.130. The routing table contains both a static route and an OSPF route for overlapping prefixes. The engineer examines the specific routing entry for 10.10.10.130. Based on the output, why does the router choose the route via 10.1.1.2 instead of the OSPF route via 10.2.2.2 (for 10.10.10.0/24)?

Accepted Answer

The static route has a longer prefix length (/26) than the OSPF route (/24), making it a more specific match.. The exhibit shows "Routing entry for 10.10.10.128/26", a /26 prefix. The router uses longest prefix match as the first step in route selection, so a /26 is more specific than the OSPF /24 and chosen regardless of AD or metric.

Answer

The static route has a lower administrative distance (1) than the OSPF route (110).

Answer

The OSPF route is inactive because its next-hop 10.2.2.2 is down.

Answer

The router prefers the static route because it has a metric of 0, which is better than the OSPF metric.

Question 12

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 13

Refer to the exhibit. An administrator is troubleshooting connectivity from a branch router R1 to the internet. A ping to 8.8.8.8 from R1 fails. The output of the show ip route command is shown. What is the most likely cause?

Accepted Answer

The next-hop IP address for the default route is not reachable.. The routing table shows the static default route 'S* 0.0.0.0/0 [1/0] via 203.0.113.1', but there is no connected or static route to network 203.0.113.0/24 (or any subnet containing 203.0.113.1). Without a route to the next-hop, the default route is unreachable, so the router cannot forward traffic to the internet, causing ping failures.

Answer

The default route is missing from the routing table.

Answer

The static route has an incorrect administrative distance.

Answer

The ip routing process has not been enabled.

Question 14

Refer to the exhibit. A network administrator is troubleshooting why not all OSPF neighbors are fully adjacent on a multi-access broadcast segment. After issuing the show ip ospf neighbor command on R1, the output is displayed. What is the most likely cause of the 2WAY/DROTHER state for neighbor 172.16.1.1?

Accepted Answer

The neighbor is a DROther and a full adjacency with another DROther is not required; adjacency is formed only with the DR and BDR.. The output shows neighbor 172.16.1.1 in state 2WAY/DROTHER. On a broadcast multi-access network (indicated by the presence of DR and BDR roles), OSPF routers that are not the DR or BDR become DROthers. DROthers reach the 2-Way state with one another but do not form full adjacencies; full adjacency is established only with the DR and BDR. Therefore, the 2WAY state is normal and expected for two DROthers. The output explicitly displays the neighbor role as DROTHER, confirming this interpretation.

Answer

The OSPF hello and dead timers are mismatched between R1 and neighbor 172.16.1.1.

Answer

The network type is configured as point-to-point on one side and broadcast on the other, causing a DR/BDR election failure.

Answer

The neighbor's router ID 172.16.1.1 is not reachable, preventing the completion of the adjacency process.

Question 15

A router has routes to 172.20.0.0/16, 172.20.10.0/24, and 172.20.10.64/26. Which route is used for traffic to 172.20.10.70?

Accepted Answer

172.20.10.64/26. The /26 route is used because it is the most specific matching prefix. In practical terms, 172.20.10.70 falls inside the 172.20.10.64/26 range, so that route narrows the destination more precisely than the broader /24 and /16 routes. Longest-prefix match therefore selects the /26 entry.

This question is designed to reinforce that specificity comes first in route lookup. Broader routes remain useful, but they lose when a more exact route matches.

Answer

172.20.0.0/16

Answer

172.20.10.0/24

Answer

The default route