JN0-363 Questions and Answers

In OSPF, an Area Border Router (ABR) that connects to a Not-So-Stubby Area (NSSA) will convert the Type 7 LSAs generated by an NSSA Autonomous System Boundary Router (ASBR) into Type 5 LSAs to advertise them into the OSPF backbone area (Area 0). Type 7 LSAs are specific to NSSAs and are used to advertise external routes within the NSSA.

References:

• Juniper Networks documentation on OSPF: OSPF Areas and LSA Types Explained

In the exhibit, the interface is configured with thenative-vlan-id 20parameter. This means that any untagged frames arriving on this interface will be associated with VLAN 20. The native VLAN serves as the default VLAN for untagged frames on a trunk port.

References:

• Juniper Networks documentation on VLANs: Configuring VLANs

The AS path is a BGP attribute that lists the autonomous systems (AS) that routing information has passed through to get to a destination. It is used to detect and prevent routing loops by checking if the router's own AS number is in the path.

References:

• Juniper Networks documentation on BGP: BGP Attributes and Policy

When deploying Link Aggregation Groups (LAGs), it is necessary for all ports in the LAG to operate at the same speed to ensure consistent performance and avoid issues with load balancing. Multi-Chassis LAG (MC-LAG) allows for the use of member links that span multiple physical devices, offering redundancy and higher bandwidth by combining the links from two separate devices into a single logical LAG.

References

• Juniper Networks Technical Documentation on Link Aggregation Groups
• Juniper Networks Technical Documentation on MC-LAG

To enable MPLS on a physical interface in Junos, the family mpls statement must be added to the interface configuration. Additionally, the interface itself must be specifiedunder the protocols mpls section of the configuration.References:

• MPLS Configuration Guide, Juniper Networks Documentation
• Configuring MPLS, Juniper Networks Documentation

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 usedby 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.

References:

• Juniper Networks documentation on Segment Routing: Segment Routing Overview

https://www.juniper.net/documentation/us/en/software/junos/mpls/topics/topic-map/lsp-routers.html

In an MPLS network, the types of routers include ingress routers (where the MPLS labels are first applied), egress routers (where MPLS labels are removed), and transit routers (which switch MPLS-labeled packets through the MPLS network). Peering routers andaggregation routers are not specific types of MPLS routers; they are general network terms.

References:

• Juniper Networks documentation on MPLS: MPLS Fundamentals

the Database Description (DD) packets serve two main purposes:

1. determinining which router is in charge of the database synchronization

2. tansferring the LSA headers between the two systems

The Database Description (DBD) OSPF packet is used during the adjacency formation process to describe the contents of the topological database between routers. The routers exchange DBD packets to determine the master and slave relationship, which dictates the router in charge of the database synchronization.References:

• OSPF Design Guide, Juniper Networks Documentation
• OSPF Database Description Packets, Juniper Networks Documentation

To influence ISP C to prefer the path through R2 for the 172.20.0.0/16 network, R2 should make its path less preferable to ISP B by prepending its AS number multiple times. This makes the path through R2 appear longer and less desirable to ISP C, which would receive these updates from ISP B. AS path length is a well-known attribute in BGP and is used to determine the best path; paths with a longer AS path are considered less preferable.

References:

• Juniper Networks documentation on BGP: BGP Path Selection and Configuration

A route being hidden in BGP usually indicates a configuration that prevents it from being used, such as a next-hop that is not reachable.B. Configuring a routing policy on R1 that sets the next-hop to the address used for IBGP peering ensures reachability of the next-hop within the local AS.D. Applying the correct routing policy as an export policy to the IBGP group on R1 will share the route with the IBGP peers, in this case, R2 and R3.References:

• Understanding BGP Path Selection, Juniper TechLibrary
• BGP Policies and Route Selection, Juniper TechLibrary

When you want to advertise an interface in OSPF but not form an OSPF adjacency over that interface (for example, towards an ISP), you can configure the interface as passive. This will advertise the network on the interface in OSPF without sending OSPF hello packets or forming OSPF neighbor relationships on that interface.

References

• Juniper Networks Technical Documentation on OSPF
• OSPF Configuration Guide - Juniper Networks

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

The Segment Routing Global Block (SRGB) defines a range of MPLS labels reserved for segment routing. With an SRGB starting label of 10,000 and an index range of 500, the first usable label is indeed 10,001 because label 10,000 is typically reserved and not usedfor forwarding. The last usable label would be 10,499 because the range includes 500 labels starting from 10,001.

References:

• Juniper Networks documentation on Segment Routing: Segment Routing Overview

The exhibit shows the configuration of a virtual switch calledsw-1with two VLANs defined within it:vlan_1with VLAN ID 1 andvlan_2with VLAN ID 2. To add interfacexe-1/0/5to the virtual switch, the interface must be associated with one of these VLANs. Since the interface is already configured withvlan-id 2, it implies that it is intended to be part ofvlan_2within the virtual switchsw-1. Therefore, the correct answer is to add interfacexe-1/0/5to thevlan_2bridge domain under thesw-1routing instance.

References:

• Juniper documentation on virtual switches: Junos OS Routing Instances Overview

In IS-IS, Level 1 routes are usually contained within the same area and Level 2 routes are used to interconnect different areas. By default, routes from Level 1 are redistributed into Level 2, and vice versa, to ensure reachability between areas.

References

• Juniper Networks Technical Documentation on IS-IS

By default, IS-IS protocol leaks routing information from a Level 1 area to a Level 2 area. However, to leak routing information from a Level 2 area to a Level 1 area, an export policy must be explicitly configured.

To test connectivity to a server from within a specific routing instance, you use thepingcommand along with therouting-instanceoption to specify the routing instance from which you are pinging. This is necessary because the routing table associated withvr3is separate from the main routing table, and you must explicitly tell the device to use thevr3routing table to reach the server.

References:

• Juniper Networks documentation on Routing Instances: Routing Instances Overview

Theshow system switchovercommand is used to display the status of the Graceful Routing Engine Switchover (GRES) feature. This command is available when nonstop routing (NSR) is enabled, which works in conjunction with GRES to maintain uninterrupted routing in case of a Routing Engine switchover.

References:

• Juniper Networks documentation on CLI Commands: show system switchover

The IPv6 header includes a new field that is not found in the IPv4 header, called the flow label. The flow label in IPv6 is used to identify packets that require special handling by routers for quality of service (QoS) or other reasons, allowing these packets to be handled efficiently as they move through the network.

References

• Juniper Networks Technical Documentation on IPv6
• IPv6 Header Fields - Juniper Networks

The exhibit shows theshow vrrp summaryoutput from two routers, with both routers listing the state of their VRRP group asmaster. VRRP allows for multiple routers to share a virtual IP address and a virtual MAC address, but usually, only one router is the master at any given time while others are in backup state. However, in some configurations, VRRP can operate in an active/active mode where multiple routers handle traffic simultaneously for load sharing. Since both routers show the state asmasterand there is no evidence of misconfiguration in the virtual IP addresses or priority, it indicates that VRRP is likely functioning in an active/active setup.

References:

• Juniper documentation on VRRP: Junos OS VRRP Overview

R2 can not forward IBGP learned routes to another IBGP neighbor correct

R3 will learn about Route X from R2 only. R1 is in a separate AS and Route X is advertised to R2 through eBGP. R2 will then advertise the route to R3 using iBGP. R3 cannot learn routes directly from another AS without having a direct eBGP session with that AS.References:

• BGP Route Propagation and Selection, Juniper Networks Documentation
• Understanding iBGP and eBGP Route Distribution, Juniper Networks Documentation