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Latest Nokia 4A0-112 Certification Practice Test Questions
NEW QUESTION # 18
Which component of the Nokia 7750 SR is in charge of performing the longest prefix match lookup on packets that arrive on the physical interfaces?
- A. Media Dependent Adapter (MDA)
- B. Control Processing Module (CMP)
- C. Switch Fabric (SF)
- D. Input/Output Module (IOM)
Answer: D
Explanation:
The Input/Output Module (IOM) is responsible for performing the longest prefix match (LPM) lookup on packets that arrive at the physical interfaces. The IOM performs this function by examining the destination IP address of incoming packets and using the routing table to determine the best match.
NEW QUESTION # 19
Refer to the exhibit.
All routers in the diagram are running a link-state routing protocol. Before the link failure, all routers have operational adjacencies with each other and there is a BFD session between routers R1 and R3. After the link failure, which of the following affects the routing protocol's convergence time?
- A. The value of the BFD transmit interval, receive interval and multiplier settings on routers R1 and R3.
- B. The time taken by the switches to detect that the physical ports are down.
- C. The value of the routing protocol hello timers on routers R1 and R3.
- D. The value of the Ethernet hello timers on the switches.
Answer: A
Explanation:
BFD (Bidirectional Forwarding Detection) is used to detect link failures quickly and helps improve convergence time in link-state routing protocols. The BFD session between routers R1 and R3 allows them to detect the failure of the link between them more quickly than the regular routing protocol hello timers. The transmit interval, receive interval, and multiplier settings determine how fast BFD detects a failure and triggers the routing protocol to converge, which directly impacts the convergence time.
NEW QUESTION # 20
What is the replacement for ARP in IPv6?
- A. Neighbor discovery procedures.
- B. Router discovery procedures.
- C. Duplicate address detection procedures.
- D. Stateless address auto-configuration procedures.
Answer: A
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 # 21
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 routers.
- B. Routers R1 and R2 are L2 routers. Routers R3 and R4 are L1/L2 routers.
- C. Routers R1 and R2 are L1/L2 routers. Routers R3 and R4 are L1 routers.
- D. All four routers are L1/L2.
Answer: C
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 # 22
Refer to the exhibit.
In the diagram, all routers are using IS-IS as their routing protocol. The number next to each link is its metric value.
What path will traffic follow from router R6 to router R3, and from router R3 to router R6?
- A. Router R6 to router R3 will follow (R6-R5-R2-R3). Router R3 to router R6 will follow (R3-R4-R2-R5-R6).
- B. Router R6 to router R3 will follow (R6-R5-R7-R4-R3). Router R3 to router R6 will follow (R3-R4-R7-R5-R6).
- C. Router R6 to router R3 will follow (R6-R5-R2-R3). Router R3 to router R6 will follow (R3-R4-R7-R5-R6).
- D. Router R6 to router R3 will follow (R6-R5-R2-R3). Router R3 to router R6 will follow (R3-R2-R5-R6).
Answer: D
Explanation:
The metric values between the routers dictate the routing paths, and IS-IS will calculate the shortest path based on these values.
R6 to R3: The path from R6 to R3 will go through R5 and R2, as this route has the least cumulative metric (10 + 10 + 15 = 35).
R3 to R6: The reverse path from R3 to R6 will follow R3 → R2 → R5 → R6 because this route is also the shortest with a total metric of 10 + 10 + 10 = 30.
NEW QUESTION # 23
Which of the following statements about router interfaces on a Nokia 7750 SR is FALSE?
- A. They can be used in pairs on the same subnet for redundancy.
- B. They can be assigned IPv4 and/or IPv6 addresses.
- C. They can be logical or physical.
- D. The system interface exists by default.
Answer: A
Explanation:
Typically, interfaces on a Nokia 7750 SR router are not configured in pairs on the same subnet for redundancy. Instead, redundancy is achieved through mechanisms like Virtual Router Redundancy Protocol (VRRP) or other high availability protocols, not by simply using interfaces in pairs on the same subnet.
NEW QUESTION # 24
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. 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.
- B. Installing two entries in the FIB for IP prefixes, one active and one in standby mode.
- C. Enabling the router to locally repair the active path to an IP prefix in case of failure.
- D. Calculating the shortest-path next hop for each known IP prefix.
Answer: D
NEW QUESTION # 25
When using IS-IS in native mode for routing in a dual-stack IPv4/IPv6 environment, which of the following statements is FALSE?
- A. In a multi-area environment, the SPF algorithm needs to be run four times on each L1/L2 router.
- B. All links are assumed to be IPv4- and IPv6-capable.
- 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: A
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 # 26
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?
- A. The equal cost multipath configuration
- B. The forwarding information base (FIB)
- C. The routing information base (RIB)
- D. The routing table manager (RTM)
Answer: D
Explanation:
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.
NEW QUESTION # 27
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 first CSNP packet from the DIS that lists the LSPs in the DIS's link-state database.
- B. Receiving a Hello packet from the DIS that contains the local router's own MAC address in the neighbor list.
- C. Receiving the last LSP requested from the DIS.
- D. Receiving a CSNP packet from the DIS acknowledging the last transmitted LSP.
Answer: A
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 # 28
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. Every router that receives the new link-state advertisement updates its age field before forwarding it.
- D. If a router receives the new link-state advertisement, it acknowledges it, stores it, and forwards it to its own neighbors.
Answer: C
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 # 29
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?
- A. Routers R2 and R4
- B. Routers R1 and R2
- C. Router R2
- D. Router R1
Answer: C
Explanation:
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.
NEW QUESTION # 30
Which of the following statements about the IP forwarding process on a router is TRUE?
- A. It uses the routing table to find a match for the source IP address.
- B. It uses the ARP table to find a match for the source MAC address.
- C. It uses the routing table to find a match for the destination IP address.
- D. It uses the ARP table to find a match for the destination MAC address.
Answer: C
Explanation:
During the IP forwarding process, routers use the routing table to determine the next hop based on the destination IP address. The source IP address is not directly involved in the lookup process for forwarding.
The ARP table is used to map IP addresses to MAC addresses, specifically for resolving the MAC address of the next hop (destination MAC address) for forwarding packets within the local network.
NEW QUESTION # 31
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 router detects that a link-state update has reached its maximum age, it will request a new update from the source router.
- 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 link-state update reaches its maximum age on a router, the router will flood that update to its neighbors.
Answer: D
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 # 32
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 has a default route and the branch office has a specific static route.
- 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 and the branch office both have default routes.
Answer: A
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 # 33
Refer to the exhibit.
Routers R1 through R4 in the diagram have established IS-IS adjacencies. Router R1 is L1/L2 and is the DIS of its two broadcast interfaces. How many LSPs will it generate?
- A. 0
- B. 1
- C. 2
- D. 3
Answer: A
Explanation:
Router R1 is configured as L1/L2, meaning it is part of both Level 1 and Level 2 IS-IS routing areas. This means R1 will generate two types of LSPs:
Level 1 LSP (for the local area 49.0001) to advertise its local topology to other Level 1 routers.
Level 2 LSP (for the backbone area 49.0002) to advertise the global network topology to Level 2 routers.
R1 also has two broadcast interfaces, and as the Designated Intermediate System (DIS) on these interfaces, it will generate an LSP for each interface (one per broadcast link).
This results in three total LSPs:
A Level 1 LSP for the local area (49.0001).
A Level 2 LSP for the backbone area (49.0002).
An LSP for each of the two broadcast interfaces, which may include interface-related topology information.
NEW QUESTION # 34
Consider the exhibit.
All routers are running IS-IS with IPv6 support enabled. Based on the topology shown, and the route tables of routers R3 and R4, which of the following statements is TRUE?
- A. Route leaking is configured on router R1 but not on router R2.
- B. Route leaking is configured on router R2 but not on router R1.
- C. There is no route leaking configured on router R1 or router R2.
- D. Route leaking is configured on both routers R1 and R2.
Answer: D
Explanation:
From the route tables of R3 and R4, we can see that remote routes are present, with R3 and R4 both having routes referencing routers in different areas (Area 49.01 and 49.02). These remote routes are characteristic of route leaking, which is the process of sharing routes between different IS-IS areas.
R3 has routes for R1, R2, and R4, which are in Area 49.01, suggesting that R1 and R2 have advertised their routes to R3, possibly due to route leaking.
R4 has similar routes for R2 and R3, indicating that R2 might have advertised its routes to R4.
This sharing of routes between areas is indicative of route leaking being configured on both R1 and R2, allowing these routes to be shared across the areas.
NEW QUESTION # 35
......
Nokia IS-IS Routing Protocol is a widely used protocol in the telecommunications industry, which offers high scalability, fast convergence, and efficient routing. It is a link-state routing protocol that uses a hierarchical structure to divide the network into areas, which helps in reducing the size of the routing table and minimizing the traffic overhead. The protocol is an essential part of any service provider's network infrastructure, and understanding its configuration and operation is critical for anyone working in the telecommunications industry.
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