JN0-363 Juniper Service Provider Routing and Switching, Specialist (JNCIS-SP) Free Practice Exam Questions (2025 Updated)

Referring to the configuration in the exhibit, R1 is set to export the 3rd_Policy to the neighbor at 192.168.1.5. Since 3rd_Policy permits the 10.200.3.0/24 prefix, only that prefix will be advertised to the neighbor.

The exhibit shows the configuration of a virtual switch called sw-1 with two VLANs defined within it: vlan_1 with VLAN ID 1 and vlan_2 with VLAN ID 2. To add interface xe-1/0/5 to the virtual switch, the interface must be associated with one of these VLANs. Since the interface is already configured with vlan-id 2, it implies that it is intended to be part of vlan_2 within the virtual switch sw-1. Therefore, the correct answer is to add interface xe-1/0/5 to the vlan_2 bridge domain under the sw-1 routing instance.

In Ethernet switching, learning and aging are two fundamental concepts for maintaining a dynamic Ethernet switching table (also known as a MAC address table). Learning is the process by which switches listen for frames and learn the MAC addresses by associating them with the incoming port. Aging is the mechanism that ensures the switch updates its table by removing MAC addresses that have not been seen for a certain amount of time (aging time).

The FE80::/10 prefix is reserved for IPv6 link-local addresses. These addresses are auto-configured on all IPv6-enabled interfaces and can be used for communication within the local link (subnet) only.

References

Juniper Networks Technical Documentation on IPv6 Addressing

https://supportportal.juniper.net/s/article/EX-Identify-the-Root-Bridge-in-a-Spanning-Tree-STP-network?language=en_US The root bridge in a spanning-tree network is the bridge with the smallest or the lowest bridge ID.

In the absence of a manually configured priority, the Spanning Tree Protocol (STP) elects the root bridge based on the lowest bridge ID, which is a combination of the priority and the MAC address. The device with the lowest MAC address will have the lowest bridge ID and thus be elected as the root bridge.

References

Juniper Networks Technical Documentation on STP

The adjacency SID in segment routing is advertised by one router to inform another about the label that should be used to forward traffic to it over a particular link. In this scenario, Router B would advertise an adjacency SID to Router A, which would be used by Router A to forward traffic to Router B. Based on the exhibit, the adjacency SID that Router B advertises to Router A would be 12.

You can see area 0.0.0.1 set for one interface and area 0.0.0.0 for the other interface. This means the router communicates in the backbone and area 1, thus it is an ABR.

Default hello timer and dead intervals are configured

hello-interval—Specifies the length of time, in seconds, before the routing device sends a hello packet out of an interface. By default, the routing device sends hello packets every 10 seconds. The range is from 1 through 255 seconds.

dead-interval—Specifies the length of time, in seconds, that the routing device waits before declaring that a neighboring routing device is unavailable. This is an interval during which the routing device receives no hello packets from the neighbor. By default, the routing device waits 40 seconds (four times the hello interval). The range is 1 through 65,535 seconds.

https://www.juniper.net/documentation/us/en/software/junos/ospf/topics/topic-map/configuring-ospf-timers.html#:~:text=The%20hello%20interval%20and%20the,devices%20on%20a%20shared%20network .

C. The R2 device is shown as having interfaces in two different OSPF areas (Area 0 and another area not specified), which makes it an Area Border Router (ABR).

D. The OSPF hello and dead intervals are set to their default values of 10 and 40 seconds, respectively.

Segment routing labels can be distributed by link-state routing protocols such as IS-IS and OSPF, which have been extended to support segment routing capabilities.

By default, BGP will propagate routes learned from EBGP peers to other IBGP peers. However, due to the BGP split-horizon rule, routes learned from one IBGP peer are not re-advertised to another IBGP peer. This behavior is designed to prevent routing information loops within the same AS.

Considering the bandwidth reservations shown, the only path from R4 to R6 that has sufficient available bandwidth for a new LSP with 400 Mbps reservation is via R1, R2, and R5. This is because the R4-R5 direct link and the R4-R1-R2-R3-R6 path do not have enough unreserved bandwidth to accommodate an additional 400 Mbps LSP.

The exhibit shows that the Label Switched Path (LSP) is down. One common reason for this could be that the IGP is not providing traffic engineering information to the MPLS process. Since the exhibit shows the OSPF configuration, enabling traffic engineering extensions for OSPF would allow OSPF to distribute the labels and traffic engineering information necessary for LSP establishment.

References

Juniper Networks Technical Documentation on MPLS and OSPF

Junos devices learn about MAC addresses by examining the source MAC address of frames received on an interface and then storing these MAC addresses in the MAC address table (also known as the forwarding database) along with the interface on which the traffic was received.

Wide metrics in IS-IS allow for a larger metric value than what is available with narrow metrics, which supports a maximum of 63. Wide metrics also enable an interface to advertise different metrics for Level 1 and Level 2, allowing for more flexible routing policies and greater scalability in large networks.

On a Junos device, trunk ports are configured to receive and transmit tagged traffic only, while access ports are configured to receive and transmit untagged traffic.

The router identifier is used by BGP and OSPF to identify the routing device from which a packet originated. The router identifier usually is the IP address of the local routing device. If you do not configure a router identifier, the IP address of the first interface to come online is used. This is usually the loopback interface. Otherwise, the first hardware interface with an IP address is used

In OSPF, if a router ID is not manually configured, Junos OS will automatically select the router ID based on the highest IP address of any of the router’s loopback interfaces. If no loopback interface exists, the highest IP address of any active interface will be used. Therefore, answer C is correct.

In VRRP (Virtual Router Redundancy Protocol), the router with the highest priority is elected as the master (primary) router. In the exhibit, routers R1 and R4 are both configured with a VRRP priority of 90. Since R2 and R3 have default priorities (which are lower than 90), they will not be elected over R1 or R4. Between R1 and R4, if all else is equal, the router with the numerically higher IP address becomes the master. However, if not enough information is provided to determine which of R1 or R4 has the higher IP address, the answer would be the one explicitly mentioned with the highest priority.

In the OSPF routing table output, prefixes are marked with different route types. An external prefix injected into OSPF is marked as 'Ext' (External) followed by a number that indicates whether it's an E1 or E2 route. The prefix 172.18.1.0/24 is marked as Ext2, which indicates that it is an external route that has been redistributed into OSPF from another routing protocol or static configuration.

References

Juniper Networks Technical Documentation on OSPF