CCNA IP Routing Practice Test 23 — 15 Questions

Question 1

You are connected to R1 via the console. R1 and R2 are configured with EIGRP AS 100. R1 has two paths to the 172.16.1.0/24 network: one via a FastEthernet link to R2 (bandwidth 100 Mbps, delay 100 microseconds) and another via a serial link to R2 (bandwidth 1.544 Mbps, delay 20000 microseconds). The EIGRP metric is calculated using the default K-values. The FastEthernet link is preferred, but you need to make the serial link the backup by adjusting the administrative distance.

Accepted Answer

Configure a static route to 172.16.1.0/24 with next-hop 10.0.0.6 and administrative distance 170.. A floating static route is configured with an administrative distance of 170, which is higher than EIGRP's default distance of 90. This ensures that the static route is only used when the EIGRP route is not available. The static route points to the next-hop IP address of R2's serial interface.

Answer

Configure a static route to 172.16.1.0/24 with next-hop 10.0.0.6 and administrative distance 90.

Answer

Configure a static route to 172.16.1.0/24 with next-hop 10.0.0.6 and administrative distance 1.

Answer

Configure a static route to 172.16.1.0/24 with next-hop 10.0.0.6 and administrative distance 255.

Question 2

You are connected to R1 via the console. R1 and R2 are running OSPFv2 in area 0. R1's router ID is 1.1.1.1, and R2's router ID is 2.2.2.2. Both routers are connected via GigabitEthernet0/0 on the 192.168.12.0/30 subnet. You need to ensure that R1 does not send OSPF hello messages out of its Loopback0 interface, while still advertising the loopback network into OSPF.

Accepted Answer

Configure the passive-interface Loopback0 command under the OSPF process.. Configuring the Loopback0 interface as passive under the OSPF process suppresses the sending of hello messages on that interface, preventing unnecessary adjacencies. The network is still advertised because OSPF includes the subnet in its LSAs.

Answer

Remove the network 192.168.12.0 0.0.0.3 area 0 command from the OSPF configuration.

Answer

Configure the ip ospf passive-interface command on GigabitEthernet0/0.

Answer

Configure the network 192.168.12.0 0.0.0.3 area 0 command under the OSPF process.

Question 3

Which three options accurately describe characteristics of OSPFv2 in a single area? (Choose three.)

Accepted Answer

OSPF uses cost as its metric, which is derived from the bandwidth of the interface.. OSPFv2 uses cost as its metric, derived from interface bandwidth using the formula cost = reference bandwidth / interface bandwidth (default reference bandwidth is 100 Mbps). Hello packets are used to discover neighbors, maintain adjacencies, and act as keepalives (default every 10 seconds on broadcast networks). The designated router (DR) is elected only on broadcast multiaccess networks (e.g., Ethernet) to reduce LSA flooding. The incorrect options: OSPFv2 does not natively support IPv6 (OSPFv3 is needed for IPv6); LSAs are refreshed every 30 minutes, not 30 seconds; router IDs must be unique across the OSPF domain, not the same in an area.

Answer

OSPFv2 supports IPv6 routing natively without any additional configuration.

Answer

OSPF routers in the same area must be configured with the same router ID.

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Link-state advertisements (LSAs) are sent periodically every 30 seconds by default.

Question 4

Which three of the following are valid features of Enhanced Interior Gateway Routing Protocol (EIGRP)? (Choose three.)

Accepted Answer

EIGRP maintains a topology table containing all routes learned from neighbors.. All three statements are correct features of EIGRP. EIGRP maintains a topology table that stores all routes learned from directly connected neighbors, including feasible successors. It uses the Diffusing Update Algorithm (DUAL) to guarantee loop-free paths by performing a diffusing computation when a route is lost. Additionally, EIGRP supports unequal-cost load balancing by using the 'variance' command, which allows traffic to be distributed across multiple paths with different metrics, as long as the metric of the alternate path is within the variance multiplier times the best metric.

Answer

EIGRP is a link-state routing protocol similar to OSPF.

Answer

EIGRP automatically summarizes routes at classful boundaries by default on all interfaces.

Answer

EIGRP uses multicast address 224.0.0.5 for all neighbor communications.

Question 5

Which three statements about IPv6 routing are correct? (Choose three.)

Accepted Answer

The next-hop address for a directly attached IPv6 static route can be a link-local address.. All three statements are correct. The 'ipv6 route' command is used to configure static routes in IPv6, similar to 'ip route' in IPv4. A directly attached IPv6 static route can indeed use a link-local address as the next hop, which is common for point-to-point interfaces. OSPFv3 (OSPF for IPv6) uses the same fundamental SPF algorithm and link-state concepts as OSPFv2 but is designed to support IPv6 addressing and runs per-link rather than per-subnet.

Answer

EIGRP for IPv6 uses the same autonomous system number as EIGRP for IPv4 and shares the same routing table.

Answer

IPv6 routing is enabled by default on all Cisco routers.

Answer

The default route in IPv6 is represented as ::/128.

Question 6

Which three of the following statements about the routing table lookup process on a Cisco router are true? (Choose three.)

Accepted Answer

The router performs a longest prefix match to select the most specific route for a destination IP.. The routing table uses longest prefix match (A) to find the most specific route. The default route (C) is used only when no other route matches. Directly connected routes (F) are automatically installed when the interface is up/up. Option D is incorrect because the router does recursively resolve the next‑hop IP when it is not directly connected.

Answer

If an exact match is found for the destination network, the router will forward the packet regardless of any more specific routes.

Answer

The router does not perform recursive resolution when the next-hop IP address is not directly connected.

Answer

The router always prefers routes with a higher administrative distance over those with a lower administrative distance.

Question 7

Two directly connected routers, R1 and R2, are configured with single-area OSPF in Area 0. The administrator notices that they are not forming a full OSPF neighbor adjacency. The exhibit displays relevant portions of the running configurations. What is the most likely cause of the problem?

Accepted Answer

R1's passive-interface default prevents OSPF hello packets from being sent on GigabitEthernet0/0.. The passive-interface default command on R1 sets all interfaces to passive by default, which prevents OSPF hello packets from being sent out GigabitEthernet0/0. Without hello packets, R1 cannot discover R2 or form a neighbor adjacency, even though the network command is correctly configured. This is the most likely cause because the exhibit shows R1's configuration includes passive-interface default without a corresponding no passive-interface GigabitEthernet0/0 statement.

Answer

The network command on R1 does not include the correct subnet mask.

Answer

The GigabitEthernet0/0 interface on R2 is administratively down.

Answer

The routers are configured with different OSPF area IDs.

Question 8

A network engineer configures a primary default route via Gi0/0 (next-hop 192.168.12.2) and a floating static default route via Gi0/1 (next-hop 192.168.12.6) with AD 200. To test failover, the engineer issues the shutdown command on Gi0/0. After this, the router does not have a default route in the routing table. Which problem explains this behavior?

Accepted Answer

The backup interface Gi0/1 is administratively down, making the next-hop unreachable.. A floating static route is installed only if its next-hop is reachable and the primary route (with lower AD) is absent. Shutting down Gi0/0 removes the primary route. However, backup interface Gi0/1 is also administratively down, so the next-hop 192.168.12.6 is unreachable, and the floating route is not installed. Option A correctly identifies the interface status as the root cause. Option B is wrong because a higher AD (200) correctly designates this as a backup; a lower AD would make it primary. Option C is false; shutting down an interface removes connected routes, which causes the recursive static route to be purged. Option D is incorrect because floating static routes do not require a track object—the AD difference alone dictates failover when the primary is removed.

Answer

The floating static route uses an administrative distance of 200, which is too low to replace the primary route.

Answer

The primary default route remains in the routing table because shutting down Gi0/0 does not remove the static route.

Answer

The floating static route is missing a track object, so the router cannot detect the primary path failure.

Question 9

A network administrator configures OSPF on two routers, R1 and R2, connected via their Serial0/0/0 interfaces (IP addresses 10.1.1.1/30 and 10.1.1.2/30). They verify that both routers use the same OSPF process ID and area 0, but R1's 'show ip ospf neighbor' shows no adjacencies. Given the partial exhibit from R1, what is the most likely cause of the adjacency failure and its correct solution?

Accepted Answer

Configure 'no passive-interface Serial0/0/0' under router ospf 1 on R1.. The most likely cause is that R1's Serial0/0/0 interface is configured as a passive interface under OSPF. When an interface is set as passive, OSPF does not send Hello packets out of it, preventing neighbor discovery and adjacency formation. The solution is to use the 'no passive-interface Serial0/0/0' command under router ospf 1 on R1, which allows Hello packets to be transmitted and the adjacency to establish.

Answer

Replace the network statement with 'network 10.1.1.0 0.0.0.255 area 0' to cover a larger range.

Answer

Change the OSPF process ID on R1 to match R2, using 'router ospf 100' and re-entering the network command.

Answer

Issue 'clear ip ospf process' on R1 to restart OSPF and reattempt neighbor discovery.

Question 10

An administrator configured a floating static default route on R1 as a backup to reach 10.10.10.0/24. The primary path is learned via OSPF, and the floating static route uses an administrative distance of 130. After the primary OSPF neighbor fails, traffic to 10.10.10.0/24 is dropped. According to the exhibit, why is the backup default route not being used?

Accepted Answer

The static route specifies an outgoing interface that is down; the next‑hop must be reachable for the route to be used.. The floating static default route is not used because the outgoing interface specified in the static route is down. For a static route with an outgoing interface to be considered valid and installed in the routing table, the interface must be in an up/up state. When the primary OSPF neighbor fails, the backup static route cannot be used because its next-hop is unreachable due to the interface being down, causing traffic to be dropped.

Answer

The administrative distance of 130 is still less than the OSPF default of 110, so it will never be installed.

Answer

The static route is missing the permanent keyword, which is required for backup routes.

Answer

The metric of the static route is too high; it should be reduced to 0.

Question 11

Drag and drop the following steps into the correct order to configure and verify OSPFv3 neighbor adjacency using link-local addresses in area 0.

Accepted Answer

Enable IPv6 unicast routing with the 'ipv6 unicast-routing' global command.. The correct order enables IPv6 unicast routing globally, creates the OSPFv3 process, enters interface configuration, assigns the interface to the OSPFv3 process in area 0 (which activates OSPFv3 on the link), and finally verifies the neighbor relationship. IPv6 unicast routing must be enabled first because OSPFv3 requires IPv6 packet forwarding. The router process must exist before an interface can be associated with it. Assigning the interface to area 0 triggers Hello packet exchange over link-local addresses. The show command confirms the adjacency formed.

Question 12

Drag and drop the following steps into the correct order to configure and verify HSRP with priority and preemption on an interface.

Accepted Answer

Enter interface configuration mode for the target interface (e.g., interface GigabitEthernet0/0).. First, enter interface configuration mode to start configuring the specific interface. Next, assign an IP address because HSRP requires a real IP on the interface for communication between HSRP routers. After that, define the HSRP group and virtual IP, which clients use as their default gateway. Then set a higher priority to influence the active router election; priority must be configured before enabling preemption, as preemption relies on priority to determine when to take over. Finally, exit configuration mode and verify with show standby to confirm the HSRP state.

Question 13

Drag and drop the following steps into the correct order to determine the best route to a destination using a routing table.

Accepted Answer

Extract the destination IP address from the packet.. The correct order follows Cisco's route selection logic: 1. Extract the destination IP (the lookup key). 2. Find all matching routes in the routing table. 3. Apply longest prefix match – the most specific route (longest subnet mask) is always preferred, regardless of administrative distance. 4. If multiple routes share that longest prefix length, compare administrative distances. 5. The route with the lowest administrative distance wins. 6. If AD values are equal (same routing protocol is typical), compare metrics. 7. The route with the lowest metric becomes the best route. This hierarchy – longest match > AD > metric – is fundamental to Cisco router behavior.

Question 14

Drag and drop the following steps into the correct order to configure an IPv4 default static route with a floating backup route on a Cisco router.

Accepted Answer

Enter privileged EXEC mode using the enable command.. The correct order is: 1. Enter privileged EXEC mode using the enable command, because you must be in privileged mode to enter global configuration. 2. Enter global configuration mode with configure terminal, as static routes are configured in global configuration. 3. Configure the primary default route using ip route 0.0.0.0 0.0.0.0 with default administrative distance (1), establishing the primary path. 4. Configure the floating backup route using ip route 0.0.0.0 0.0.0.0

(e.g., 10), so it is less preferred. 5. Exit global configuration mode using end to return to privileged EXEC. 6. Save the configuration with copy running-config startup-config to ensure the routes persist after a reboot.

Question 15

Drag and drop the following steps into the correct order to configure single‑area OSPFv2 on a router, advertise the 192.168.10.0/24 and 10.0.0.0/24 networks in area 0, and set the GigabitEthernet0/0 interface as passive.

Accepted Answer

Enter global configuration mode using the 'configure terminal' command.. The correct sequence is: (1) Enter global configuration mode with 'configure terminal' – this is required before any configuration commands. (2) Initiate the OSPF process with 'router ospf 1' – this places the CLI into OSPF router configuration mode where the remaining commands are issued. (3) Advertise the 192.168.10.0/24 network in area 0 – the 'network' command must be issued under OSPF router mode to inject the connected network into OSPF. (4) Advertise the 10.0.0.0/24 network – a second 'network' statement; the order of network commands is interchangeable but they must be configured before setting passive interfaces in a logical workflow. (5) Configure GigabitEthernet0/0 as a passive interface – this prevents OSPF Hello packets and neighbor adjacency on that interface while still advertising its subnet, and it is configured under OSPF router mode. (6) Return to privileged EXEC mode with 'end' – exits configuration mode and returns to the enable prompt. While setting a passive interface before the network statement does not break the configuration, Cisco documentation suggests adding networks first to clearly define which interfaces participate in OSPF before applying passive-interface restrictions.