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Nokia is a well-known brand in the telecommunications industry, and it offers a wide range of products and services. Among its offerings is the Nokia 4A0-112 exam, which covers the Nokia IS-IS routing protocol. 4A0-112 exam is designed to test the knowledge and skills of networking professionals who work with Nokia's products and services.
NEW QUESTION # 19
For a link-state routing protocol, which of the following statements about link-state updates is FALSE?
- A. The age value is updated as the link-state update is flooded throughout the network and when it is in the link-state database
- B. When a link-state update reaches its maximum age on a router, the router will flood that update to its neighbors.
- C. Aging helps ensure that routers that are no longer part of the topology will eventually get removed from the link-state database.
- D. When a router detects that a link-state update has reached its maximum age, it will request a new update from the source router.
Answer: B
Explanation:
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 This prevents outdated information from continuing to affect the routing decisions.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.
NEW QUESTION # 20
A series of actions are triggered on a router as a result of enabling both loopfree-alternate for a link-state routing protocol and ip-fast-reroute. Which of the following is NOT one of those actions?
- A. Enabling the router to locally repair the active path to an IP prefix in case of failure.
- B. Calculating a backup next hop for each known IP prefix, if it exists, that would not create a routing loop if used without informing other routers.
- C. Calculating the shortest-path next hop for each known IP prefix.
- D. Installing two entries in the FIB for IP prefixes, one active and one in standby mode.
Answer: C
NEW QUESTION # 21
A router running a link-state routing protocol detects that one of its neighbors is no longer connected to it. The router generates a new link-state advertisement to inform other routers of the topology change. Which of the following is NOT an action that is triggered by this event?
- A. If a router receives multiple copies of the new link-state advertisement, it will simply ignore all copies received after the first one.
- B. Every router that receives the new link-state advertisement runs the SPF algorithm to recalculate its shortest-path tree and its forwarding database.
- C. If a router receives the new link-state advertisement, it acknowledges it, stores it, and forwards it to its own neighbors.
- D. Every router that receives the new link-state advertisement updates its age field before forwarding it.
Answer: D
Explanation:
When a router receives a link-state advertisement (LSA), it does not update the age field before forwarding it. The age field in an LSA is typically updated by the originating router or during the process of forwarding the LSA within the network. Routers do not modify the age field upon receiving and forwarding an LSA.
NEW QUESTION # 22
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?
- A. The head office and the branch office both have default routes.
- B. The head office and the branch offices both have specific static routes.
- C. The head office has a specific static route and the branch office has a default route.
- D. The head office has a default route and the branch office has a specific static route.
Answer: D
Explanation:
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.
NEW QUESTION # 23
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?
- A. Routers R1 and R2 are L2 routers. Routers R3 and R4 are L1/L2 routers.
- B. Routers R1 and R2 are L1/L2 routers. Routers R3 and R4 are L1 routers.
- C. All four routers are L1/L2.
- D. Routers R1 and R2 are L2 routers. Routers R3 and R4 are L1 routers.
Answer: B
Explanation:
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.
NEW QUESTION # 24
What do the address resolution protocol (ARP) for IPv4 and the neighbor discovery procedures for IPv6 have in common?
- A. Both detect duplicate MAC address assignments.
- B. Both resolve a host device's IP address using its MAC address.
- C. Both resolve a host device's MAC address using its IP address.
- D. Both detect duplicate IP address assignments.
Answer: C
Explanation:
ARP for IPv4 and Neighbor Discovery Protocol (NDP) for IPv6 are both used to map a device's IP address to its MAC address. This is essential for communication within a local network.
ARP is used in IPv4 networks, and NDP performs a similar function in IPv6 networks, ensuring devices can communicate effectively on the same network segment.
NEW QUESTION # 25
Which of the following is NOT a function of the control plane a router?
- A. To determine the best way to forward packets.
- B. To utilize the forwarding tables to forward data packets towards their destination.
- C. To exchange signaling messages with other routers.
- D. To establish routing paths to deliver packets from source to destination and to reestablish them in case of failure.
Answer: B
Explanation:
The data plane (or forwarding plane) is responsible for actually forwarding the data packets. It uses the information stored in the forwarding table to determine how to move packets from one interface to another toward their destination.
NEW QUESTION # 26
An IS-IS router receives a CSNP that references an older LSP than the one in its local database. What action is taken?
- A. The router sends a PSNP to its neighbor to request a copy of the LSP.
- B. The router sends a copy of the referenced LSP from its database to its neighbor.
- C. The router updates its database with the new sequence number and floods a copy of the LSP to its other neighbors.
- D. The router sends a CSNP to its neighbor describing the newer LSPs in its database.
Answer: B
Explanation:
When a router receives a CSNP (Complete Sequence Number PDU) that references an older LSP (Link-State PDU) than the one in its local database, it indicates that the neighbor is missing newer information.
In response, the router sends back a PSNP (Partial Sequence Number PDU) to the neighbor, which includes a copy of the LSPs it has in its local database that the neighbor may not yet have. This helps to synchronize the link-state information between routers.
NEW QUESTION # 27
Which of the following definitions best describes route redistribution?
- A. It is the process of controlling which route advertisements received from routing peers are accepted and/or deciding which locally known prefixes are advertised to routing peers.
- B. It is the process of deciding at line-rate speed which packets will be dropped and which ones will be forwarded.
- C. It is the process of redirecting packets to be processed by an intermediate network function before allowing them to be forwarded to their intended final destination.
- D. It is the process of passing routing information from one routing domain to another, which usually means from one routing protocol to another.
Answer: D
Explanation:
Route redistribution is the process of sharing routing information between different routing protocols or routing domains. For example, a router might redistribute routes learned via OSPF into a BGP routing table or vice versa. This enables routers to exchange routing information even when they are using different routing protocols.
NEW QUESTION # 28
When using IS-IS in native mode for routing in a dual-stack IPv4/IPv6 environment, which of the following statements is FALSE?
- A. All links are assumed to be IPv4- and IPv6-capable.
- B. In a multi-area environment, the SPF algorithm needs to be run four times on each L1/L2 router.
- C. The same topology information is used to calculate the shortest path tree for both IPv4 and IPv6.
- D. It may lead to traffic black-holing if not properly designed.
Answer: B
Explanation:
In a dual-stack IPv4/IPv6 IS-IS environment, the SPF (Shortest Path First) algorithm is only run once per router for each protocol (IPv4 or IPv6). The topology is shared, but the SPF calculations for IPv4 and IPv6 are separate. This means that the SPF algorithm will run twice (once for IPv4 and once for IPv6) for each L1/L2 router, not four times.
NEW QUESTION # 29
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?
- A. Detailed topology information is only shared among routers within the same area, thus reducing the complexity of the SPF calculation.
- B. Less-capable routers can be isolated from having to keep track of IP prefixes that are external to the local routing domain.
- C. Fewer routers are required to handle the same amount of traffic, as compared to a single-area domain.
- D. Route tables can be reduced by summarizing the IP prefixes advertised between areas.
Answer: C
Explanation:
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.
NEW QUESTION # 30
There are several differences between IS-IS Hello packets used on broadcast interfaces and on point-to-point interfaces.
Which of the following statements is FALSE?
- A. Broadcast Hello messages identify the elected designed IS (DIS) and point-to-point Hello messages do not.
- B. On broadcast interfaces there are different Hello packet types for level-1 and level-2 adjacencies, whereas on point-to-point interfaces there is a single Hello packet type.
- C. The neighbors are identified using their interface MAC addresses on broadcast Hello messages and using their system IDs on point-to-point Hello messages.
- D. The multicast MAC addresses to which the Hello messages are sent are different on broadcast interfaces and on point-to-point interfaces.
Answer: C
Explanation:
In both broadcast and point-to-point interfaces, IS-IS routers identify neighbors using system IDs, not interface MAC addresses. The system ID is a unique identifier assigned to each router, and it is used to identify neighbors in both types of interfaces.
NEW QUESTION # 31
Which of the following statements about IS-IS is FALSE?
- A. A router becomes level-2 when it is associated with the backbone area.
- B. IS-IS uses the concept of level-1 and level-2 routers to implement hierarchy.
- C. A level-1 router forwards traffic to other areas through the nearest I eve I-1/1 eve I-2 router.
- D. In IS-IS, routers are associated with an area, not the interfaces.
Answer: D
Explanation:
In IS-IS, routers are actually associated with interfaces rather than the entire router being associated with a single area. A router can have interfaces in multiple areas, and it is the interface's configuration that determines which area it belongs to.
NEW QUESTION # 32
A router is trying to establish an IS-IS adjacency with the DIS on a broadcast link. What event causes the adjacency to change from "Initializing" to "UP"?
- A. Receiving the last LSP requested from the DIS.
- B. Receiving a CSNP packet from the DIS acknowledging the last transmitted LSP.
- C. Receiving a Hello packet from the DIS that contains the local router's own MAC address in the neighbor list.
- D. Receiving the first CSNP packet from the DIS that lists the LSPs in the DIS's link-state database.
Answer: D
Explanation:
The process of establishing an IS-IS adjacency on a broadcast link involves several steps, and the transition from the Initializing state to the UP state occurs when both routers exchange sufficient information to confirm they have a consistent view of the link-state database.
The CSNP (Complete Sequence Number PDU) packet is used to advertise the list of LSPs in the router's link-state database. When a router receives the first CSNP from the DIS (Designated Intermediate System) that lists the LSPs in the DIS's database, it indicates that the router has enough information to establish the adjacency and synchronize its database.
NEW QUESTION # 33
What is the replacement for ARP in IPv6?
- A. Router discovery procedures.
- B. Neighbor discovery procedures.
- C. Stateless address auto-configuration procedures.
- D. Duplicate address detection procedures.
Answer: B
Explanation:
In IPv6, the Neighbor Discovery Protocol (NDP) replaces the Address Resolution Protocol (ARP) used in IPv4. NDP is responsible for several functions, including resolving IP addresses to MAC addresses (similar to ARP), detecting duplicate IP addresses, and discovering other devices on the network.
NEW QUESTION # 34
A routing domain is using a single-area link-state routing protocol. Which of the following is NOT information that a router can share with other routers in the domain using protocol-specific messages?
- A. The local router ID and the router IDs of neighboring routers.
- B. The IP prefixes of subnets directly attached to the router.
- C. A copy of the local routing table.
- D. IP prefixes known by the router because it is running ad additional routing protocol.
Answer: C
Explanation:
In a single-area link-state routing protocol (such as OSPF), routers share specific information about the network topology, not their entire routing table. They exchange link-state advertisements (LSAs) that contain information about their directly connected interfaces and their state, allowing other routers to build a consistent view of the network.
NEW QUESTION # 35
Refer to the exhibit.
Routers R1 through R4 are running an IGP in such a way that they have each other's system IP addresses in their routing tables. A static route is configured on router R1 so that it can reach subnetwork 10.4.100.0/24. The network administrator decides to use an indirect static route, as shown in the diagram. However, pinging the server from router R1 fails. What may be the problem in this case?
- A. Router R1 drops the echo request because address 10.10.10.3 does not belong to an adjacent router.
- B. Router R3 drops the echo request because it does not have subnet 10.4.100.0/24 in its routing table.
- C. The echo request arrives at the server but there is no path for the echo response to return to router R1.
- D. Router R2 drops the echo request because it does not have subnet 10.4.100.0/24 in its routing table.
Answer: C
Explanation:
The static route configured on router R1 uses an indirect next-hop, which is 10.10.10.3 (R3). While the echo request from R1 reaches the server through the IGP, the problem lies in the return path for the echo response.
The route 10.4.100.0/24 is reachable through R3, but there is no reciprocal route in R3's routing table that allows the response to flow back towards R1. This results in a failure to return the echo response to R1, causing the ping to fail.
NEW QUESTION # 36
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