Be able to trace multicast RPF failures, configure MSDP peers with MD5 authentication at the correct hierarchy, and verify BSR, C-RP, and group state with Junos operational commands. The critical skill is confirming the exact RPF path and source of truth before changing configuration.
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Domain overview
This domain covers IP multicast on Junos, including PIM sparse and dense modes, RPF checking, MSDP peering between autonomous systems, and BSR/C-RP operation. Questions are scenario-based: you diagnose forwarding failures, identify correct configuration hierarchies, and select operational commands to verify group, source, and RP state.
Exam objectives
PIM RPF failure causes, including route, interface, and tunnel mismatches
MSDP peer configuration hierarchy and MD5 TCP session authentication
BSR and Candidate-RP election and message processing verification
Multicast forwarding table and group/source state inspection commands
Assuming RPF failure is always a unicast routing problem, ignoring tunnel, interface, and policy conditions that also break the check.
Configuring the MSDP MD5 key at the wrong hierarchy instead of under the peer, so TCP authentication never applies.
Treating BSR election success as proof that C-RP messages are processed, without checking RP and BSR state separately.
Click any question to see the full explanation and answer options, or start a focused practice session above.
A network administrator needs to display the multicast routing table entries, including incoming interfaces and outgoing interface lists (OIL), on a Junos device. Which operational command should be used?
2An administrator wants to configure MSDP (Multicast Source Discovery Protocol) between two autonomous system border routers to share active source information. Which configuration hierarchy in Junos is used to define the MSDP peer relationship?
3An enterprise design requires configuring an Anycast RP setup using two Junos routers to provide redundancy for PIM sparse-mode. Which mechanism is required to synchronize source state information between the two Anycast RPs within the same AS?
4Which IPv4 multicast address range is designated for Source-Specific Multicast (SSM) operations according to IANA standards?
5An engineer configures protocol independent multicast (PIM) sparse-mode on a Junos device and notices that join messages are not reaching the Rendezvous Point (RP). Which CLI command should the engineer use to verify the operational state of the PIM neighbor adjacencies and confirm that the hello messages are successfully exchanged?
6An engineer needs to view the MSDP Source-Active (SA) cache on a Junos router to verify which sources are currently active across different PIM domains. Which operational command should be executed?
7An engineer needs to verify which multicast groups have active receivers joined on an interface using IGMP. Which operational command should be used?
8Which operational command is used to verify the operational status and peer state of MSDP sessions on a Junos device?
9An administrator wants to configure Candidate-RP (C-RP) advertisements using the Bootstrap Router (BSR) mechanism in PIM sparse-mode. Which hierarchy level in Junos is used to configure the local router as a Candidate-RP?
10Which protocol version introduces explicit source inclusion and exclusion lists (TO_EX, TO_IN, IS_IN, IS_EX) in membership reports?
11An administrator wants to configure an MSDP peer relationship on a Junos device and ensure that the MD5 password authentication is applied to the TCP session. Where is the MD5 authentication key configured for an MSDP peer?
12Which IPv4 address is assigned as the all-systems multicast group address, used by routers to query all hosts on a local subnet?
13An enterprise design uses PIM sparse-mode with a BSR. An engineer notices that the router has successfully elected a BSR, but no Candidate-RP messages are being processed. Which operational command should the engineer use to verify the BSR candidate information and elected BSR address on the router?
14An engineer wants to configure a Junos router to act as a Bootstrap Router (BSR) for PIM sparse-mode. Which configuration hierarchy is used to enable the BSR function?
15An enterprise network uses multiple routing instances with PIM sparse-mode. An engineer needs to configure Inter-AS multicast routing using MSDP. Which component is required to establish MSDP peering across different autonomous systems where BGP is also running?
16An engineer needs to verify the Rendezvous Point (RP) currently learned via the Bootstrap Router (BSR) mechanism on a Junos device. Which operational command should be used?
17An engineer is configuring PIM sparse-mode in an enterprise network. Which TWO characteristics are true regarding PIM sparse-mode operation? (Choose two)
18An administrator is troubleshooting an MSDP deployment between two autonomous systems. Which THREE factors can cause an MSDP peer session to fail to establish? (Choose three)
19Which TWO statements are correct regarding IGMP version 2 (IGMPv2) features compared to IGMPv1? (Choose two)
20Which TWO statements describe the function and operation of a PIM Bootstrap Router (BSR)? (Choose two)
21An engineer is troubleshooting multicast forwarding and RPF failures on a Junos routing instance. Which THREE conditions will cause a multicast RPF check failure? (Choose three)
22An enterprise network uses MBGP (Multicast BGP) alongside PIM sparse-mode. Which THREE statements accurately describe the function of MBGP in a multicast environment? (Choose three)
23An administrator is configuring IGMP snooping on an EX Series switch. Which TWO benefits does IGMP snooping provide in a switched Ethernet environment? (Choose two)
24An administrator is configuring a Junos device to support IGMPv3 on user-facing VLAN interfaces. Which configuration statement enables IGMPv3 processing on interface irb.10?
25A network engineer must implement Anycast RP using MSDP between two data center routers running Junos OS. Which statement correctly describes a core requirement for MSDP peer establishment?
26An enterprise has deployed MSDP between two independent PIM sparse-mode domains. An administrator notices that Source-Active (SA) messages are looping between MSDP peers. Which Junos mechanism should be configured to prevent SA message loops in an MSDP topology?
27A network administrator is configuring an enterprise router to join the Source-Specific Multicast (SSM) range. According to RFC standards, what is the standard IPv4 address block reserved for SSM?
28An engineer is troubleshooting a multicast forwarding issue where data from a specific source is not reaching receivers in a remote PIM sparse-mode domain. Which THREE operational commands and diagnostic steps should be used to verify the multicast forwarding state and RPF path on a Junos router? (Choose three)
29An enterprise network runs PIM sparse-mode with a static RP. A Junos router receives a PIM Register message from a directly connected first-hop router for a new multicast source. The router is the RP for that group. Which action does the RP take upon receiving the Register message?
30You administer a Junos router that has two equal-cost paths toward the PIM rendezvous point for group 239.1.1.1. Users report intermittent multicast outages whenever the unicast route to the RP flaps. You want to eliminate the dependency on unicast reachability to the RP for this group. Which configuration accomplishes this?
31A network engineer is troubleshooting a PIM Sparse-Mode domain where multicast traffic from a source is not reaching receivers. The engineer suspects that the Rendezvous Point (RP) is not receiving PIM Register messages from the First-Hop Router (FHR). Which TWO statements describe reasons why the FHR might fail to send Register messages to the RP? (Choose two.)
32An enterprise network runs PIM sparse-mode with a static RP configured on all routers. Users on a VLAN report that they can receive multicast streams from external sources, but the internal server 10.10.5.20 streaming to group 239.1.1.1 was just migrated to a new subnet. After the migration, receivers on a different VLAN stop receiving the stream, even though the new subnet is reachable and PIM is enabled on all interfaces. Which configuration element is most likely missing?
33A Junos router is the last-hop router for receivers in VLAN 100. The receivers use IGMPv3 and request group 239.5.5.5 from source 10.10.10.10 only. The router has a PIM sparse-mode shared tree (*,G) toward the RP, but traffic from 10.10.10.10 is not being delivered to the receivers. The unicast route to 10.10.10.10 points out a different interface than the one toward the RP. Which action resolves the problem?
34An administrator is enabling PIM sparse-mode on a Junos router that connects to a Layer 2 switch carrying several user VLANs. Receivers on those VLANs need to join multicast groups, but the router is not seeing any IGMP membership reports from the hosts. PIM is enabled on the router's interface toward the switch. Which action is required on the router to receive IGMP reports?
35A Junos router connects to a Layer 2 switch that has multiple receivers on VLAN 200. The switch is not running PIM, and the router is the only multicast router on the segment. You want the router to send IGMP general queries on the VLAN 200 interface and track receiver group memberships. Which configuration is required?
36An ISP engineer is troubleshooting an interdomain multicast deployment. A receiver in AS 65001 wants to receive a stream sourced in AS 65002. The RP in AS 65001 has no (S,G) state for the source, and the RP in AS 65002 is not sending any Source-Active messages. Both RPs are configured as MSDP peers over a working TCP session. Which statement explains why the RP in AS 65001 lacks source information?
37An engineer is deploying PIM sparse-mode with anycast RP using two Junos routers that share the loopback address 10.0.0.1/32. Both routers are configured as static RPs for all groups and as MSDP peers with each other using their unique loopback addresses. Receivers attached to Router A join a group whose source is registered with Router B. Traffic initially flows, but after Router B reloads, receivers lose the stream even though Router A still has the anycast RP address reachable. Which mechanism is responsible for restoring source information to Router A?
Be able to trace multicast RPF failures, configure MSDP peers with MD5 authentication at the correct hierarchy, and verify BSR, C-RP, and group state with Junos operational commands. The critical skill is confirming the exact RPF path and source of truth before changing configuration.
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