Nokia 4A0-112 Exam Practice Test Instant Access

Question 1

When multiple routing protocols offer a route for the same prefix, what part of the router is in charge of deciding which route to make active?

AThe routing information base (RIB)

BThe routing table manager (RTM)

CThe equal cost multipath configuration

DThe forwarding information base (FIB)

Answer : B

The routing table manager (RTM) is responsible for selecting the best route when multiple routing protocols provide a route for the same destination prefix. It makes the decision on which route to add to the routing table based on the administrative distance, metric, and other criteria.

Question 2

Refer to the exhibit.

Static routing is to be used in a network between a corporate head office and a branch office. The head office has many connected subnetworks, whereas the branch office has one subnetwork and a single connection to the head office. Which of the following is the most likely configuration on the head office and branch office routers?

AThe head office has a default route and the branch office has a specific static route.

BThe head office and the branch offices both have specific static routes.

CThe head office and the branch office both have default routes.

DThe head office has a specific static route and the branch office has a default route.

Answer : A

The head office has many connected subnetworks, so it will typically have a default route to forward traffic to the branch office (or external networks), since it may not need to define static routes for each branch network.

The branch office, which has only one subnetwork and a single connection to the head office, will have a specific static route to reach the head office subnet or other subnets at the head office, since it only needs to know the specific route to reach the head office's network.

Question 3

Two IS-IS neighboring routers are trying to establish an adjacency, but the interface has been configured as broadcast on one of them and as point-to-point on the other. Why is the adjacency not established?

AThe routers do not agree on the result of the DIS election.

BThe routers discard the received Hello messages because they are not the expected type: LAN Hello vs point-to-point Hello.

CThe routers do not receive each other's Hello messages because they listen for messages transmitted to different multicast MAC addresses.

DThe routers do not receive each other's Hello messages because they listen for messages transmitted to different multicast IP addresses.

Answer : B

IS-IS routers use different types of Hello messages depending on whether the interface is configured as a broadcast (LAN) or point-to-point (P2P) link.

On a broadcast network (e.g., Ethernet), IS-IS routers use LAN Hello packets to establish adjacencies.

On a point-to-point link, IS-IS uses point-to-point Hello packets.

If one router is configured for a broadcast interface and the other for point-to-point, they will exchange incompatible Hello packets, and as a result, neither router will accept the other's Hello messages, preventing the adjacency from being established.

Question 4

A routing domain uses a link-state routing protocol. Which of the following would NOT be an advantage of dividing the entire routing domain into areas?

ADetailed topology information is only shared among routers within the same area, thus reducing the complexity of the SPF calculation.

BRoute tables can be reduced by summarizing the IP prefixes advertised between areas.

CLess-capable routers can be isolated from having to keep track of IP prefixes that are external to the local routing domain.

DFewer routers are required to handle the same amount of traffic, as compared to a single-area domain.

Answer : D

Dividing a domain into areas typically does not reduce the number of routers needed to handle traffic. It is more focused on improving scalability, reducing the size of routing tables, and limiting the scope of SPF calculations, but it doesn't inherently reduce the number of routers required.

Question 5

For a link-state routing protocol, which of the following statements about link-state updates is FALSE?

AWhen a link-state update reaches its maximum age on a router, the router will flood that update to its neighbors.

BWhen a router detects that a link-state update has reached its maximum age, it will request a new update from the source router.

CAging helps ensure that routers that are no longer part of the topology will eventually get removed from the link-state database.

DThe age value is updated as the link-state update is flooded throughout the network and when it is in the link-state database

Answer : A

When a link-state update reaches its maximum age, it is removed from the router's link-state database, not flooded to its neighbors. This prevents outdated information from continuing to affect the routing decisions. The router does not flood the aged update; instead, it will typically request a new link-state advertisement from the original source router if the information is still needed.

Question 6

Refer to the exhibit.

Routers R1, R2, R3, and R4 are running IS-IS. Assuming all interfaces are added to IS-IS as point-to-point and no commands are issued at the interface level to restrict adjacencies, which of the following statements is TRUE?

ARouters R1 and R2 are L2 routers. Routers R3 and R4 are L1 routers.

BRouters R1 and R2 are L2 routers. Routers R3 and R4 are L1/L2 routers.

CRouters R1 and R2 are L1/L2 routers. Routers R3 and R4 are L1 routers.

DAll four routers are L1/L2.

Answer : C

From the output, we can see that the usage column indicates whether a router is operating as an L1 or L2 router:

The L1/L2 designations refer to whether the routers participate in both Level 1 and Level 2 of IS-IS:

In this case, R1 and R2 are L2 routers, and R3 and R4 are L1 routers.

Question 7

Refer to the exhibit.

In the IS-IS network shown, router R1 has been configured to summarize subnetworks 20.20.1.0/24 and 20.20.2.0/24 as 20.20.0.0/16. Which routers' routing tables will be reduced, compared to their routing tables before the summarization?

ARouter R1

BRouter R2

CRouters R1 and R2

DRouters R2 and R4

Answer : B

Router R1 is the one that performs the summarization of the two subnets (20.20.1.0/24 and 20.20.2.0/24) into the summarized route 20.20.0.0/16. However, R1 itself will not see any change in its routing table because it is directly connected to both subnets and already knows about them.

Router R2, which is in Area 49.0002, will benefit from this summarization because it previously had separate routes for both 20.20.1.0/24 and 20.20.2.0/24. After the summarization, R2 will only need to maintain a single route to 20.20.0.0/16, reducing the size of its routing table.

Router R4 does not directly benefit from the summarization because it is only connected to the Level 1 network and has no need for the summarized routes from R1. Thus, the summarization does not affect R4's routing table.

Nokia IS-IS Routing Protocol 4A0-112 Exam Practice Test