CCNA IP Routing Practice Test 24 — 15 Questions

Question 1

A router learns a route to 172.16.0.0/16 via OSPF (administrative distance 110) and a route to 172.16.10.0/24 via EIGRP (administrative distance 90). No other overlapping routes exist. Which TWO statements about how the router handles these routes are correct?

Accepted Answer

Both the OSPF and EIGRP routes are installed in the routing table.. B is correct because the router installs both routes in the routing table when they have different prefix lengths. The EIGRP route to 172.16.10.0/24 (AD 90) is more specific than the OSPF route to 172.16.0.0/16 (AD 110). The router uses the longest prefix match rule for forwarding, so both routes coexist without conflict.

Answer

The router installs only the EIGRP route because it has a lower administrative distance.

Answer

Traffic to 172.16.10.100 is forwarded using the OSPF route.

Answer

The EIGRP route is used for all traffic destined to any address within 172.16.0.0/16.

Question 2

An enterprise network uses an IPv6 dual-stack design. Router R1 has a primary default route ::/0 via 2001:db8:1::1 with AD 1 and a floating default route with AD 10 via link-local address fe80::2. After the primary link fails, the floating route fails to install, and R1 loses all external connectivity. The administrator confirms the backup interface is up/up.

Accepted Answer

The floating static route uses a link-local next-hop but does not specify an exit interface, making the route incomplete.. Option B is correct because a floating static route using a link-local next-hop (fe80::2) must also specify an exit interface (e.g., GigabitEthernet0/1) to be considered complete. Without the exit interface, the router cannot determine which interface to use for neighbor discovery, leaving the route incomplete and unable to be installed into the routing table. This is a common requirement for IPv6 static routes with link-local addresses, as the next-hop is not globally unique.

Answer

The administrative distance of the backup route is 10, so it is not installed while the primary route still exists.

Answer

The floating static route will be installed only if the primary link is administratively shut down, not after a physical failure.

Answer

The next-hop fe80::2 is unreachable because IPv6 neighbor discovery is disabled on the backup interface.

Question 3

An administrator has just configured OSPF in a single area between router R1 and router R2, which are directly connected via their Gi0/0 interfaces with IP addresses 10.0.0.1/30 and 10.0.0.2/30. On R1, the command show ip ospf neighbor shows no entries, and a further check on R2 with show ip ospf interface gi0/0 indicates that the interface is passive. Which configuration error is most likely causing the adjacency failure?

Accepted Answer

R2 has the passive-interface default command but no no passive-interface command for Gi0/0.. The output on R2 shows the Gi0/0 interface is passive, meaning OSPF will not send or receive hello packets on that interface, preventing neighbor discovery. The passive-interface default command makes all interfaces passive by default, and without a no passive-interface Gi0/0 command, the interface remains passive, blocking adjacency formation. This directly explains why R1's show ip ospf neighbor shows no entries.

Answer

The network command on R1 does not cover the 10.0.0.0/30 subnet.

Answer

The OSPF process IDs on R1 and R2 are mismatched.

Answer

The hello and dead intervals on R1 and R2 are not the same.

Question 4

A network engineer notices that traffic from the router to server 192.168.10.5 is being sent over a slow backup link, even though the primary high-speed link is up. The routing table has an OSPF route for 192.168.10.0/24 via the primary link and a static host route to 192.168.10.5/32 via the backup link. Why is the backup link used for traffic to the server?

Accepted Answer

The static /32 route is a more specific match than the OSPF /24 route, so it is selected regardless of administrative distance.. The router uses the most specific matching route in the routing table to forward traffic. The static host route to 192.168.10.5/32 has a longer prefix length (32 bits) than the OSPF route for 192.168.10.0/24 (24 bits), making it a more specific match. Even though OSPF has a higher administrative distance, the longest prefix match rule takes precedence over administrative distance when both routes are present in the routing table.

Answer

The static route has an administrative distance of 1, which is lower than OSPF's 110, so it is always preferred.

Answer

The router is load-balancing between the two routes, and traffic is being hashed to the backup link for this particular flow.

Answer

The OSPF route is not installed in the routing table because the static route has a better AD.

Question 5

A network administrator has configured HSRP between RouterA and RouterB for VLAN 10. End hosts using the virtual IP 192.168.1.1 as their default gateway experience intermittent connectivity losses, and pings to 192.168.1.1 often fail. The output of 'show standby brief' on both routers shows the state as Active. What is the most likely cause?

Accepted Answer

The routers are configured with mismatched HSRP authentication methods.. When both routers show the HSRP state as Active, a 'dual-active' scenario exists, which causes intermittent connectivity because both routers forward traffic for the virtual IP. Mismatched HSRP authentication methods (e.g., one router using plain-text authentication and the other using MD5) prevent the routers from exchanging proper Hello messages, so they fail to negotiate a single Active router. This is the most likely cause because authentication mismatches break the HSRP adjacency, leading to both routers assuming the Active role.

Answer

The virtual IP address is configured on only one router.

Answer

The HSRP group number on one router is set to 0.

Answer

The priority on both routers is configured to the same value.

Question 6

Drag and drop the following steps into the correct order to configure a primary default static route and a floating default static route on a Cisco router.

Accepted Answer

Enter global configuration mode using the configure terminal command.. First, enter global configuration mode. Then configure the primary default route (no administrative distance specified, default 1). Next, configure the floating default route with a higher administrative distance (e.g., 5). Exit configuration mode, and finally verify the static routes in the routing table.

Question 7

Drag and drop the following steps into the correct order to configure Router R1 with OSPFv2 process 1 to form neighbor adjacencies only on GigabitEthernet0/1 while preventing OSPF hello packets on all other OSPF-enabled interfaces.

Accepted Answer

router ospf 1. First, enter OSPF router configuration mode. Then assign a Router ID (optional but good practice). Next, advertise the local subnet with a network statement to enable OSPF on interfaces. Then apply passive-interface default to suppress hellos on all OSPF interfaces. Finally, use no passive-interface to allow adjacency on the specific interface.

Question 8

Which TWO statements about floating static routes and default routes are correct?

Accepted Answer

A floating static route uses an administrative distance higher than that of the primary route to act as a backup.. Option A is correct because a floating static route is configured with a higher administrative distance (AD) than the primary route. This ensures the floating route remains inactive in the routing table unless the primary route fails, at which point the router installs the floating static route as a backup. The higher AD makes it less preferred than the primary dynamic or static route.

Answer

A floating static route must have a lower administrative distance than the primary route to ensure faster convergence.

Answer

Floating static routes are supported only for IPv6, not for IPv4.

Answer

A default static route cannot be configured as a floating static route.

Question 9

Refer to the exhibit. A network engineer is troubleshooting an OSPF adjacency issue between R1 and R2. The output of the show ip ospf neighbor command on R1 shows the neighbor relationship with R2 stuck in the EXSTART/DROTHER state. What is the most likely cause?

Accepted Answer

MTU mismatch on the link between R1 and R2, causing DBD packets to be dropped.. The output specifically shows neighbor 10.0.0.2 in the EXSTART/DROTHER state. This state indicates that the Database Description (DBD) packet exchange phase has not completed. The most common cause for a neighbor to remain stuck in EXSTART is an MTU mismatch on the link, causing DBD packets (which are larger than the MTU) to be silently dropped.

Answer

OSPF network type mismatch between R1 and R2, preventing full adjacency.

Answer

Duplicate OSPF Router IDs on R1 and R2, causing DBD packet rejection.

Answer

OSPF authentication mismatch on the link, causing DBD packets to be rejected.

Question 10

A technician is troubleshooting an OSPF adjacency problem: R1 and R2 are not forming a neighbor relationship. R1's OSPF configuration includes the command 'network 192.168.1.0 0.0.0.255 area 0'. R2's GigabitEthernet0/0 is configured with IP address 10.1.1.1/30 and is participating in OSPF area 0. The engineer verifies that physical connectivity is fine and OSPF is enabled on R2. What is the most likely cause?

Accepted Answer

R1's network statement does not include the subnet of the link connecting R1 and R2.. R1's network statement uses a wildcard mask of 0.0.0.255, which exactly matches interfaces with IP addresses in the 192.168.1.0/24 range. The link between R1 and R2 uses the 10.1.1.0/30 subnet, so R1's interface on that link will have an IP address that does not fall within the network command. Because OSPF only activates on interfaces whose primary IP is covered by a network statement, OSPF is not running on R1's connecting interface; no Hello packets are sent, and the adjacency cannot form. The other options describe possible causes but do not align with the given configuration: no explicit network type change is mentioned, duplicate router-IDs are not indicated, and no timer modification is described.

Answer

The OSPF network type on R1's interface differs from the network type on R2's interface.

Answer

R1's router ID is not manually set and duplicates the router ID of R2.

Answer

Mismatched OSPF hello and dead intervals between the routers.

Question 11

Refer to the exhibit. A network technician is troubleshooting router R1, which cannot reach hosts on the internet. R1 is connected to an ISP router at 203.0.113.1. The exhibit shows the output of the show ip route command. What is the most likely cause of the issue?

Accepted Answer

A static default route is not configured on R1, and OSPF is not advertising a default route.. The exhibit shows 'Gateway of last resort is not set' and no route entry for 0.0.0.0/0 (default route). Without a default route, R1 has no path to forward unknown destinations, such as internet hosts. The OSPF neighbor is active (192.168.2.0/24 learned via OSPF), but no default route is being originated by OSPF. Therefore, a static default route or OSPF default-information originate command is missing.

Answer

The OSPF neighbor relationship with the ISP router is down.

Answer

The interface connecting to the ISP router is in a shutdown state.

Answer

An incorrect next-hop address was specified in the static default route, making the route invalid.

Question 12

A network engineer notices that R1 is using the static route to 192.168.10.0/24 via next-hop 10.1.1.2 instead of the OSPF route via 10.2.2.2, even though the OSPF path has lower latency. What is the most likely cause?

Accepted Answer

The static route has a lower administrative distance than the OSPF route.. The static route is preferred because it has an administrative distance (AD) of 1, which is lower than OSPF's AD of 110. When multiple routes to the same destination exist from different routing sources, the route with the lowest AD is selected first. The static route's path might be slower, but AD comparison happens before any metric comparison. To use the OSPF path, the static route must be removed or given a higher AD.

Answer

The OSPF route has a higher metric than the static route.

Answer

Equal-cost multi-path (ECMP) is disabled for OSPF.

Answer

The static route is configured with a higher next-hop IP address, so it is preferred.

Question 13

Refer to the exhibit. A network administrator is troubleshooting an OSPF adjacency on R1's GigabitEthernet0/0 interface connected directly to R2. R2 is powered on and shows correct OSPF configuration, but the adjacency is stuck in the INIT or DOWN state. Based on the output, what is the most likely cause of the failure?

Accepted Answer

The OSPF passive-interface command has been applied to GigabitEthernet0/0, preventing hello packets from being sent.. The command output explicitly shows 'No Hellos (Passive interface)', confirming that the passive-interface command has been applied to GigabitEthernet0/0. With this configuration, OSPF does not send or receive hello packets on the interface, preventing any adjacency from forming with the directly connected neighbor R2.

Answer

The OSPF network type on R1's GigabitEthernet0/0 does not match the network type on R2.

Answer

The OSPF hello and dead timers on R1 do not match those configured on R2.

Answer

The GigabitEthernet0/0 interface on R1 has been assigned to a different OSPF area than R2's connected interface.

Question 14

A network engineer configures a static route: ip route 192.168.10.0 255.255.255.0 10.1.1.2. The next hop 10.1.1.2 is reachable via OSPF. Later, the engineer notices that the route to 192.168.10.0/24 has disappeared from the routing table. What is the most likely cause?

Accepted Answer

The OSPF route to 10.1.1.0/30 has been lost, making the next-hop address 10.1.1.2 unresolvable.. A recursive static route uses a next-hop IP address; the router must have a route that resolves that next hop. If the OSPF route to the 10.1.1.0/30 network is lost, the next-hop 10.1.1.2 becomes unreachable, and the static route is withdrawn from the routing table. None of the other explanations account for the route disappearance given the scenario.

Answer

The static route has a higher administrative distance than OSPF, so OSPF's route to 192.168.10.0/24 replaced it.

Answer

The static route uses a next-hop IP address that is not directly connected, which is unsupported on this platform.

Answer

A routing loop caused by recursive lookups has suppressed the static route to prevent loops.

Question 15

R1 loses its route to 192.168.20.0/24 whenever R2's GigabitEthernet0/0 interface flaps. The network engineer has configured a floating static route with an administrative distance of 200. The OSPF route has an AD of 110. After R2's G0/0 interface recovers, the floating static route appears in the routing table instead of the OSPF route. What should the technician do next?

Accepted Answer

Check the carrier delay timers on R2's GigabitEthernet0/0 interface.. The next step is to check the carrier delay timers on R2's G0/0 interface. If a high debounce (carrier-delay) timer is configured, the interface remains down for several seconds after physical link recovery. During this time OSPF neighbor adjacency cannot form, so the floating static route (which is already installed) remains in the table. This is a Layer 2/Layer 1 timing issue that directly impacts OSPF convergence.

Answer

Adjust the administrative distance of the floating static route to 201.

Answer

Clear the IP routing table and reset the OSPF process on R1.

Answer

Verify that the MTU on R1 and R2's GigabitEthernet0/0 interfaces match.