Important Juniper JN0-351 Exam Questions

Answer: B, C, D

Explanation:

BFD is a protocol that can be used to quickly detect failures in the forwarding path between two adjacent routers or switches. BFD can be integrated with various routing protocols and link aggregation protocols to provide faster convergence and fault recovery.

According to the Juniper Networks documentation, the following protocols support BFD on Junos OS devices1:

BGP: BFD can be used to monitor the connectivity between BGP peers and trigger a session reset if a failure is detected.BFD can be configured for both internal and external BGP sessions, as well as for IPv4 and IPv6 address families2.

OSPF: BFD can be used to monitor the connectivity between OSPF neighbors and trigger a state change if a failure is detected.BFD can be configured for both OSPFv2 and OSPFv3 protocols, as well as for point-to-point and broadcast network types3.

LACP: BFD can be used to monitor the connectivity between LACP members and trigger a link state change if a failure is detected.BFD can be configured for both active and passive LACP modes, as well as for static and dynamic LAGs4.

Other protocols that support BFD on Junos OS devices are:

IS-IS: BFD can be used to monitor the connectivity between IS-IS neighbors and trigger a state change if a failure is detected. BFD can be configured for both level 1 and level 2 IS-IS adjacencies, as well as for point-to-point and broadcast network types.

RIP: BFD can be used to monitor the connectivity between RIP neighbors and trigger a route update if a failure is detected. BFD can be configured for both RIP version 1 and version 2 protocols, as well as for IPv4 and IPv6 address families.

VRRP: BFD can be used to monitor the connectivity between VRRP routers and trigger a priority change if a failure is detected. BFD can be configured for both VRRP version 2 and version 3 protocols, as well as for IPv4 and IPv6 address families.

The protocols that do not support BFD on Junos OS devices are:

RSTP: RSTP is a spanning tree protocol that provides loop prevention and rapid convergence in layer 2 networks. RSTP does not use BFD to detect link failures, but relies on its own hello mechanism that sends BPDU packets every 2 seconds by default.

FTP: FTP is an application layer protocol that is used to transfer files between hosts over a TCP connection. FTP does not use BFD to detect connection failures, but relies on TCP's own retransmission and timeout mechanisms.

1: [Configuring Bidirectional Forwarding Detection]2: [Configuring Bidirectional Forwarding Detection for BGP]3: [Configuring Bidirectional Forwarding Detection for OSPF]4: [Configuring Bidirectional Forwarding Detection for Link Aggregation Control Protocol] : [Configuring Bidirectional Forwarding Detection for IS-IS] : [Configuring Bidirectional Forwarding Detection for RIP] : [Configuring Bidirectional Forwarding Detection for VRRP] : [Understanding Rapid Spanning Tree Protocol] : [Understanding FTP]

Answer: A, D

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.

Answer: B, D

Explanation:

Junos devices support various types of tunnels for different purposes12.

Option B is correct.Generic Routing Encapsulation (GRE) is a tunneling protocol that can encapsulate a wide variety of network layer protocols inside virtual point-to-point links over an Internet Protocol network1.Junos devices support GRE tunnels1.

Option D is correct.IPsec (Internet Protocol Security) is a protocol suite for securing Internet Protocol (IP) communications by authenticating and encrypting each IP packet of a communication session1.Junos devices support IPsec tunnels1.

Option A is incorrect. Spanning Tree Protocol (STP) is not a type of tunnel.It's a network protocol designed to prevent loops in a bridged Ethernet local area network2.

Option C is incorrect.While Junos devices do support IP-IP (also known as IP tunneling), it's not supported on all Junos devices1.

Answer: C, D

Explanation:

The routers that are directly connected to the Dallas and Denver subnets are not advertising the connected subnets.This can be resolved by redistributing the connected subnets into OSPF1.

Option C suggests to configure and apply a routing policy that redistributes the connected Dallas and Denver subnets.This is correct because redistribution allows routes from one routing protocol to be communicated to another, and in this case, it allows the connected subnets to be advertised through OSPF1.

Option D suggests enabling the passive option on the OSPF interfaces that are connected to the Dallas and Denver subnets.This is also correct because in OSPF, a passive interface is an interface that belongs to the OSPF router, but does not send OSPF Hello packets1.It's typically used on an interface that you don't want to use for OSPF adjacencies, but you still want to advertise its IP address1. Therefore, enabling passive interface can help in advertising the Dallas and Denver subnets.

Answer: D

Explanation:

In OSPF, the Designated Router (DR) and Backup Designated Router (BDR) are elected based on the priority of the routers1.The router with the highest priority becomes the DR, and the router with the second highest priority becomes the BDR1.If there is a tie in priority, then the router with the highest Router ID is chosen1.

In this scenario, R2 has a higher priority (64) than R1 (32), so R2 will become the DR1.Since R1 has the second highest priority, it will become the BDR1. Therefore, option D is correct.