CCNA IP Routing Practice Test 15 — 15 Questions

Question 1

Based on the exhibit, why is traffic to host 198.51.100.70 using the OSPF route instead of the static route?

Accepted Answer

Because the OSPF /26 route is more specific than the static /24 route.. The traffic uses the OSPF route because it is the more specific match. In practical terms, the router evaluates destination-prefix specificity before comparing route source preference. The static route points to a broader /24, while the OSPF entry points to a narrower /26 that still contains the destination. Because longest-prefix match comes first, the /26 route wins.

This is a good reminder that static routes do not automatically beat dynamic routes when the prefixes are different. Specificity matters first, then source preference only when the prefix length is the same.

Answer

Because OSPF always overrides static routing, regardless of prefix length.

Answer

Because the static route must have an administrative distance of 255 to be considered.

Answer

Because the destination 198.51.100.70 is outside both listed routes.

Question 2

A branch router uses PPP on a serial WAN link. Which additional PPP capability most directly improves access security on that link?

Accepted Answer

PPP authentication. PPP authentication most directly improves access security on the link. In practical terms, authentication helps verify the identity of the peer rather than simply bringing up the point-to-point connection without validation. That makes PPP more useful than a bare unauthenticated link in environments where peer identity matters.

At CCNA level, the important point is recognizing that PPP is associated with optional authentication capability on WAN links.

Answer

STP root election

Answer

Wireless roaming

Answer

IPv6 loopback addressing

Question 3

A router has a static route for 172.16.10.128/25 and an OSPF-learned route for 172.16.10.0/24. When forwarding traffic to 172.16.10.130, why does the router use the static route instead of the OSPF route?

Accepted Answer

Because the static /25 route is more specific than the OSPF /24 route.. The static route is used because it is the more specific match. In practical terms, route selection starts with prefix specificity. The destination 172.16.10.130 matches both routes shown, but the static /25 is more specific than the OSPF /24. Because longest-prefix match comes first, the static route is chosen regardless of the different route sources.

This is a classic route-selection interpretation question that tests whether you prioritize specificity correctly.

Answer

Because static routes always beat OSPF even when they are less specific.

Answer

Because OSPF routes cannot be used for Class B networks.

Answer

Because the OSPF metric is lower than the static administrative distance.

Question 4

Which two statements accurately describe why BGP is often relevant at an Internet or multi-provider edge?

Accepted Answer

It is associated with routing between autonomous systems.. BGP is often relevant at the edge because it is associated with route exchange between autonomous systems and large external routing domains. In practical terms, this makes it a natural protocol to discuss where organizations connect to providers or exchange external reachability. It is not just another interior campus protocol.

The question is about conceptual fit, not deep BGP attribute tuning.

Answer

It is mainly used to replace STP on access switches.

Answer

It is required before DHCP relay can function.

Answer

It is the protocol used by CAPWAP for AP discovery.

Question 5

You are verifying OSPF operation on router R1. After confirming that OSPF is configured on the correct interfaces, which command should you use next to directly check whether R1 has established a neighbor adjacency with another OSPF router?

Accepted Answer

show ip ospf neighbor. The command show ip ospf neighbor directly displays the OSPF neighbor table, showing whether an adjacency has formed, the neighbor's Router ID, and the current state (e.g., FULL). This is the quickest verification step after confirming configurations. The other commands are unrelated to OSPF: show vlan brief displays VLAN assignments, show spanning-tree shows STP topology, and show mac address-table shows the MAC address table. None of these provide any OSPF neighbor information and would only delay troubleshooting.

Answer

show vlan brief

Answer

show spanning-tree

Answer

show mac address-table

Question 6

Based on the exhibit, what is the most likely reason the PPP link is down?

Accepted Answer

The serial interfaces use different encapsulations.. The PPP link is down because the two ends are configured for different encapsulations. In practical terms, one side is using PPP and the other is using HDLC, so the devices are not speaking the same data-link protocol on the serial link. Until those encapsulations match, the link cannot come up correctly at the data-link layer.

This is a classic WAN troubleshooting pattern that fits well into simulation-style exam coverage.

Answer

PPP requires CAPWAP on both routers.

Answer

The routers must run BGP before PPP can establish.

Answer

Serial links can use only OSPF, not PPP.

Question 7

What is the best explanation for why a router chooses the OSPF route to 10.50.0.0/16 instead of the RIP route?

Accepted Answer

Because OSPF has a lower administrative distance than RIP for the same prefix.. The router chooses the OSPF route because when the prefix length is the same, source preference is considered, and OSPF has a lower administrative distance than RIP. In practical terms, both routes describe the same destination size, so longest-prefix match does not separate them. The router then trusts the OSPF source more than RIP by default.

This is a classic administrative-distance comparison question and a very important route-selection concept.

Answer

Because RIP routes are never installed when OSPF is running.

Answer

Because OSPF always has a longer prefix than RIP.

Answer

Because the RIP metric is lower than the OSPF metric.

Question 8

R1 and R2 are connected via Ethernet and are configured with OSPF, but they fail to form an adjacency. Upon checking the interface configurations, you see that R1’s interface is in OSPF area 0 while R2’s interface is in area 1, and both interfaces use default timers and are in the same subnet. What is the most likely reason?

Accepted Answer

The OSPF areas do not match on the shared segment.. The most likely cause is an OSPF area mismatch on the shared segment. R1 and R2 are in the same IP subnet and use default hello/dead timers, so neither subnet mismatch nor timer mismatch is the problem. OSPF can run on Ethernet interfaces. However, OSPF requires neighbors on the same link to agree on the area ID; here they differ, preventing adjacency. Option B is incorrect because OSPF process IDs are locally significant and do not need to match.

Answer

The routers must use the same process ID.

Answer

The interfaces are in different IPv4 subnets.

Answer

OSPF cannot run on Ethernet interfaces.

Question 9

Based on the exhibit, why is traffic to 192.168.40.200 using the default route instead of the intended static route?

Accepted Answer

The static route next hop is unreachable or invalid for forwarding.. The intended static route is not being used because the next hop for that static route is not reachable from the current routing table. In practical terms, a route can be configured, but the router still needs a way to resolve and forward to the next-hop address. If that next hop is unreachable, the route may not be installed or usable, so traffic falls back to the default route instead.

This is a realistic troubleshooting pattern because the configuration line alone can look correct until you compare it with actual reachability.

Answer

Default routes always override static routes.

Answer

The destination must be configured as a /16, not a /24.

Answer

Static routes can be used only if OSPF is disabled.

Question 10

Based on the exhibit, what is the most likely reason the PPP link is failing to authenticate?

Accepted Answer

The PPP authentication credentials do not match between the two sides.. The most likely reason is a credentials mismatch between the two sides of the PPP authentication setup. In practical terms, PPP authentication requires the peers to agree on the relevant identity and secret information. If those values do not align, the link may come up physically but authentication fails and the logical connection does not establish properly.

This is a very exam-relevant WAN troubleshooting scenario because it focuses on a realistic failure after the transport is already present.

Answer

The interfaces must use HDLC instead of PPP before authentication can work.

Answer

CHAP requires the routers to be in different IPv4 subnets.

Answer

PPP authentication works only over GRE tunnels.

Question 11

Based on the exhibit, which command is the best next step to verify whether the floating static route becomes active after the primary route is lost?

Accepted Answer

show ip route. The best next step is to examine the routing table directly after removing or losing the primary route. In practical terms, the purpose of a floating static route is to appear when the better route disappears. The clearest way to verify that behavior is to inspect the route table for the default route after the failure condition.

This is a simulation-style verification question. It is not asking how to configure the route, but how to confirm failover actually happened.

Answer

show vlan brief

Answer

show spanning-tree

Answer

show power inline

Question 12

Why is R1 not installing the floating static default route into the routing table?

Accepted Answer

Because the OSPF default route has a lower administrative distance than the floating static route.. The floating static default route is not installed because the primary default route is already present and has a lower administrative distance. In practical terms, a floating static route is meant to sit in reserve and appear only when the preferred route is unavailable. Since the OSPF default route is active and has a better administrative distance, the backup route is not used yet.

This is a classic route-preference question. The key idea is not just that a static route exists, but that a higher-distance static route is intentionally designed to lose until the primary path disappears.

Answer

Because static default routes can never be used when OSPF is enabled.

Answer

Because the static default route must use a /24 mask instead of 0.0.0.0.

Answer

Because the next hop of a floating route must be a loopback address.

Question 13

Why is traffic to 10.10.10.200 using the EIGRP route instead of the OSPF route, given that both routes have the same prefix length?

Accepted Answer

Because EIGRP has a lower administrative distance than OSPF for the same prefix length.. When two routes have the same prefix length, the router uses administrative distance to choose the route with the lowest value. EIGRP has a default administrative distance of 90, while OSPF uses 110. Therefore, the EIGRP route is preferred.

Answer

Because OSPF routes are never installed when EIGRP is present.

Answer

Because OSPF can be used only for IPv6 routes.

Answer

Because EIGRP routes always have a smaller subnet mask than OSPF routes.

Question 14

A router has a static route configured: ip route 10.200.0.0 255.255.0.0 GigabitEthernet0/1. The output of show ip interface brief shows that interface GigabitEthernet0/1 is administratively down. Why is the route to 10.200.0.0/16 present in the running configuration but absent from the routing table?

Accepted Answer

Because the route points to an interface that is administratively down.. The static route is absent because the outgoing interface is down. In practical terms, when a static route depends on an interface that is not operational, the router cannot use that path, so the route is not installed as usable forwarding state. The configuration line alone is not enough; the forwarding path also has to be viable.

This is a realistic static-route troubleshooting pattern because it distinguishes between configured intent and operational state.

Answer

Because static routes cannot reference exit interfaces.

Answer

Because the destination must be a /24, not a /16.

Answer

Because static routes require NTP before installation.

Question 15

R1 and R2 are connected via a GigabitEthernet link in the same IPv4 subnet, and both routers have OSPF configured in the same area. However, R1 is not learning any OSPF routes from R2. What is the most likely cause?

Accepted Answer

GigabitEthernet0/0 is configured as a passive OSPF interface on R1.. The most likely reason is that one side has the interface configured as passive, which prevents OSPF hello packets from being sent on that interface. In practical terms, the network statement alone does not guarantee neighbor formation. OSPF still needs active neighbor discovery on the link. If the interface is passive, the router advertises the connected network into OSPF but does not attempt to form an adjacency there.

This is a realistic routing troubleshooting pattern because the configuration can look mostly correct until you inspect the passive-interface setting.

Answer

The routers must use different OSPF process IDs to exchange routes.

Answer

The routers are in different IPv4 subnets.

Answer

OSPF can advertise routes only across serial links.