JN0-351 Online Practice Questions and Answers

Correct Answer: B

Correct Answer: BC

Correct Answer: B

Correct Answer: C

Correct Answer: A

Correct Answer: B

Explanation: The configuration shown in the exhibit is an example of a routing instance of type virtual-router. A routing instance is a collection of routing tables, interfaces, and routing protocol parameters that create a separate routing domain

on a Juniper device1. A virtual-router routing instance allows administrators to divide a device into multiple independent virtual routers, each with its own routing table2. The configuration also includes a rib-group statement, which is used to

import routes from one routing table to another. A rib-group consists of an import-rib statement, which specifies the source routing table, and an export-rib statement, which specifies the destination routing table.

In this case, the rib-group name is inet-to-ispi, and the import-rib statement specifies inet.0 as the source routing table. The export-rib statement specifies ispi.inet.0 as the destination routing table. This means that the routes from inet.0 will be

imported into ispi.inet.0. Therefore, the correct answer is B. The inet.0 route table will be imported into the ispi.inet.0 route table.

References:

1: Routing Instances Overview 2: Virtual Routing Instances : [rib-group (Routing Options)]

Correct Answer: B

The exhibit shows the configuration of BFD liveness detection for BGP at the global level, which applies to all BGP neighbors by default1. However, this configuration does not specify the session mode, which determines whether BFD uses

single-hop or multihop mode to communicate with a neighbor2. For single-hop BGP neighbors, which are directly connected on the same subnet, the session mode can be either automatic or single-hop. For multihop BGPneighbors, which are

not directly connected and require multiple hops to reach, the session mode must be multihop2.

Since your BGP neighbors are in different countries, they are likely to be multihop neighbors. Therefore, you need to configure the session mode as multihop for each neighbor individually at the [edit protocols bgp group group-name neighbor

address bfd-liveness-detection] hierarchy level2. For example:

protocols { bgp { group usa { neighbor 192.0.2.1 { bfd-liveness-detection { session-mode multihop; } } } group france { neighbor 198.51.100.1 { bfd-liveness-detection { session-mode multihop; } } } } }

If you do not configure the session mode for multihop neighbors, BFD will use the default mode of automatic, which will try to use single-hop mode and fail to establish a BFD session with the remote neighbor2. This will prevent BGP from

using BFD to detect liveliness and failover.

Therefore, the answer B is correct, as you need to configure the BFD liveness detection on the BGP neighbor level with the appropriate session mode for multihop neighbors.

Correct Answer: B

The exhibit shows the output of the command show ospf neighbor, which displays information about the OSPF neighbors on a router1. The output shows that the OSPF neighbor with the address 172.26.1.1 and the interface ge-0/0/3.0 is in the Exstart state1. The Exstart state is the fourth state in the OSPF neighbor formation process, after Down, Init, and 2-Way states2. In this state, the OSPF neighbors establish a master-slave relationship and exchange database description (DBD) packets, which contain summaries of their link-state databases2. The most common reason for OSPF neighbors to be stuck in the Exstart state is an MTU mismatch between the interfaces3. MTU stands for maximum transmission unit, which is the largest size of a packet that can be transmitted on a network segment4. If the MTU values of two OSPF neighbors are different, theymay not be able to exchange DBD packets successfully, as some packets may be dropped or fragmented due to their size exceeding the MTU limit3. To solve this problem, you need to ensure that the MTU values of both OSPF neighbors are the same or compatible. You can use the command show interfaces to display the MTU value of an interface5. You can also use the command ping with the do-not-fragment option to test the MTU size between two routers. You can change the MTU value of an interface by using the command set interfaces interface-name mtu mtu-value in configuration mode5.

Correct Answer: BD

Explanation: The two reasons for the failure to form an adjacency in a network running IS- IS could be:

B. There is no configured ISO address on any IS-IS interface. IS-IS requires each router interface to have an ISO address configured. Without this address, the routers cannot form an adjacency1.

D. The family iso configuration is missing from the adjacency interface. The `family iso' configuration is essential for IS-IS to function correctly. If this configuration is missing from the adjacency interface, it could prevent the formation of an adjacency1. These explanations are based on the Enterprise Routing and Switching Specialist (JNCIS- ENT) documents and learning resources available at Juniper Networks23.

Correct Answer: AD

Explanation: In Rapid Spanning Tree Protocol (RSTP), there are several port roles that determine the behavior of the port in the spanning tree1. Option A suggests that the designated port forwards data to the downstream network segment or device. This is correct because the designated port is the port on a network segment that has the best path to the root bridge1. It's responsible for forwarding frames towards the root bridge and sending configuration messages into its segment1. Option D suggests that the root port is responsible for forwarding data to the root bridge. This is also correct because the root port is always the link directly connected to the root bridge, or the shortest path to the root bridge1. It's used to forward traffic towards the root bridge1. Therefore, options A and D are correct.