Juniper JN0-351 Enterprise Routing and Switching, Specialist Exam Practice Test

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Total 65 questions
Question 1

What are two characteristics of RSTP alternate ports? (Choose two.)



Answer : A, C

Ais correct because RSTP alternate ports block traffic while receiving superior BPDUs from a neighboring switch.An alternate port is a backup port for a root port, which means it receives better BPDUs from another bridge than the current root port1.However, an alternate port does not forward any traffic, as it is in a discarding state2. It only listens to BPDUs and waits for the root port to fail.If the root port fails, the alternate port can immediately transition to a forwarding state and become the new root port1.

Cis correct because RSTP alternate ports provide an alternate higher cost path to the root bridge.An alternate port is selected based on the same criteria as the root port, which are the lowest bridge ID, the lowest path cost, the lowest sender port ID, and the lowest receiver port ID3.However, an alternate port receives a higher cost BPDU than the root port, otherwise it would be the root port itself1. Therefore, an alternate port provides an alternate higher cost path to the root bridge than the root port.


Question 2

Exhibit

Your ISP is announcing a default route to both R1 and R2. You want your network routers to forward all Internet traffic through the R1 device

Which BGP attribute would you use?



Answer : C

The BGP attribute that you would use to forward all Internet traffic through the R1 device is thelocal preference1.

The local preference is an attribute that is used within an autonomous system (AS) and exchanged between iBGP routers1.It is used to select an exit point from the AS1.The path with the highest local preference is preferred1.By setting a higher local preference for the routes received from R1, you can make R1 the preferred exit point for all Internet traffic1.


Question 3

You are a network operator who wants to add a second ISP connection and remove the default route to the existing ISP You decide to deploy the BGP protocol in the network.

What two statements are correct in this scenario? (Choose two.)



Answer : A, B

Ais correct because IBGP updates the next-hop attribute to ensure reachability within an AS. This is because the next-hop attribute is the IP address of the router that advertises the route to a BGP peer. If the next-hop attribute is not changed by IBGP, it would be the IP address of an external router, which may not be reachable by all routers within the AS.Therefore, IBGP updates the next-hop attribute to the IP address of the router that received the route from an EBGP peer1.

Bis correct because IBGP peers advertise routes received from EBGP peers to other IBGP peers. This is because BGP follows the rule of advertising only the best route to a destination, and EBGP routes have a higher preference than IBGP routes.Therefore, IBGP peers advertise routes learned from an EBGP peer to all BGP peers, including both EBGP and IBGP peers1.


Question 4

What is the maximum allowable MTU size for a default GRE tunnel without IPv4 traffic fragmentation?



Answer : D

The maximum allowable MTU size for a default GRE tunnel without IPv4 traffic fragmentation is1476 bytes1.This is because GRE packets are formed by the addition of the original packets and the required GRE headers1.These headers are 24-bytes in length and since these headers are added to the original frame, depending on the original size of the packet we may run into IP MTU problems1.The most common IP MTU is 1500-bytes in length (Ethernet)1.When the tunnel is created, it deducts the 24-bytes it needs to encapsulate the passenger protocols and that is the IP MTU it will use1.For example, if we are forming a tunnel over FastEthernet (IP MTU 1500) the IOS calculates the IP MTU on the tunnel as: 1500-bytes from Ethernet - 24-bytes for the GRE encapsulation = 1476-Bytes1.


Question 5

Exhibit

You are a network operator troubleshooting BGP connectivity.

Which two statements are correct about the output shown in the exhibit? (Choose two.)



Answer : B, C

Option B suggests that the BGP session is not established. This is correct because in the output, the state of the BGP session is shown as ''Idle''.In BGP, an ''Idle'' state means that the BGP session is not currently established1.

Option C suggests that R1 is configured for AS 65400.This is also correct because in the output, it's shown that the local AS number is 654001.The local AS number represents the Autonomous System (AS) number of the router on which you're checking the BGP session1.


Question 6

You are configuring an IS-IS IGP network and do not see the IS-IS adjacencies established. In this scenario, what are two reasons for this problem? (Choose two.)



Answer : A, D

Option A suggests that the MTU is not at least 1492 bytes.This is correct because IS-IS requires a minimum MTU of 1492 bytes to establish adjacencies1.If the MTU is less than this, IS-IS adjacencies will not be established1.

Option D suggests that the lo0 interface is not included as an IS-IS interface.This is also correct because the loopback interface (lo0) is typically used as the router ID in IS-IS1.If the loopback interface is not included in IS-IS, it could prevent IS-IS adjacencies from being established1.

Therefore, options A and D are correct.


Question 7

Which statement is correct about IP-IP tunnels?



Answer : A

IP-IP tunnels are a type of tunnels that use IP as both the encapsulating and encapsulated protocol. IP-IP tunnels are simple and easy to configure, but they do not provide any security or authentication features. IP-IP tunnels only support encapsulating IP traffic, which means that the payload of the inner packet must be an IP packet.IP-IP tunnels cannot encapsulate non-IP traffic, such as Ethernet frames or MPLS labels1.

Option A is correct, because IP-IP tunnels only support encapsulating IP traffic. Option B is incorrect, because IP-IP tunnels only support encapsulating non-IP traffic. Option C is incorrect, because the TTL in the inner packet is not decremented during transit to the tunnel endpoint.The TTL in the outer packet is decremented by each router along the path, but the TTL in the inner packet is preserved until it reaches the tunnel endpoint2. Option D is incorrect, because there are 20 bytes of overhead with IP-IP encapsulation.The overhead consists of the header of the outer packet, which has a fixed size of 20 bytes for IPv43.


1:IP-IP Tunneling2:What is tunneling? | Tunneling in networking3: IPv4 - Header

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Total 65 questions