Multicast Practice Questions

Answers and explanations appear when you work through the set above.

1. In PIM Sparse Mode, what message type is sent by a Designated Router (DR) to register a new multicast source directly with the Rendezvous Point (RP)?

   • PIM Join/Prune
   • PIM Register
   • IGMP Membership Report
   • PIM Assert

2. Which IGMP version added support for Source-Specific Multicast (SSM), allowing clients to request stream traffic from specific unicast source IPs?

   • IGMPv1
   • IGMPv2
   • IGMPv3
   • CGMP

3. In Protocol Independent Multicast (PIM) Sparse Mode, how is the Designated Router (DR) elected on a multi-access broadcast network segment?

   • Highest PIM DR Priority, then highest IP address.
   • Lowest IP address, then the longest neighbor uptime.
   • A hash of each router's Loopback0 address, highest wins.
   • Static assignment only; there is no automatic election.

4. What feature on Layer 2 switches prevents multicast traffic from flooding every port on a VLAN by inspecting IGMP membership reports?

   • PIM Dense Mode
   • IGMP Snooping
   • Storm Control
   • CGMP

5. In PIM Sparse Mode, which dynamic Rendezvous Point mechanism uses Cisco proprietary announcements sent over UDP port 496 to group address 224.0.1.39 / 224.0.1.40?

   • Static RP
   • Auto-RP
   • PIM Bootstrap Router (BSR)
   • Anycast RP

6. When a host leaves a multicast group in IGMPv2, to which destination IP address does it send an IGMP Leave Group message?

   • 224.0.0.1 (All-Hosts)
   • 224.0.0.2 (All-Routers)
   • 224.0.0.13 (PIM Routers)
   • The specific multicast group IP address being left

7. Which IANA IPv4 multicast address block is specifically designated for Source-Specific Multicast (SSM) applications?

   • 224.0.0.0/24
   • 224.0.1.0/24
   • 232.0.0.0/8
   • 239.0.0.0/8

8. In PIM Sparse Mode, how is the Designated Router (DR) selected on a multiaccess Ethernet segment?

   • Lowest interface IP address, with the longest PIM neighbor uptime breaking ties.
   • Highest PIM DR Priority (default 1), with the highest IP address breaking ties.
   • The router that holds a static Rendezvous Point mapping for the multicast groups.
   • The switch with the highest base MAC address on the segment, as in STP root election.

9. Which major functionality enhancement was introduced in IGMPv3 compared to IGMPv2?

   • Automatic distribution of Rendezvous Point to group mappings to every host on the local segment.
   • Source-Specific Multicast support: hosts can request traffic from specific source addresses.
   • Encryption of IGMP messages and multicast frames at Layer 2 between host and switch.
   • Automatic conversion of IPv4 multicast groups into IPv6 multicast addresses for MLD.

10. In PIM Sparse Mode, what path representation corresponds to a Source Tree versus a Shared Tree in the multicast routing table (mroute)?

    • Source Tree = (*, G); Shared Tree = (S, G)
    • Source Tree = (S, G); Shared Tree = (*, G)
    • Source Tree = (VLAN, Port); Shared Tree = (IP, MAC)
    • Source Tree = (RP, DR); Shared Tree = (IGMP, PIM)

11. What purpose does Multicast Source Discovery Protocol (MSDP) serve when deploying Anycast RP within a PIM Sparse Mode domain?

    • It encapsulates multicast user traffic inside GRE tunnels between the anycast RPs.
    • It shares Source-Active messages about active sources between the RPs over TCP.
    • It converts IPv6 multicast groups into IPv4 broadcasts for legacy receivers.
    • It elects a single active RP among the anycast RPs and keeps the others on standby.

12. In PIM Sparse Mode (PIM-SM), what primary role does the Rendezvous Point (RP) perform in multicast traffic delivery?

    • It acts as the default gateway for all unicast traffic leaving the multicast routing domain.
    • It is the meeting point where sources register and receivers join the shared tree (*, G).
    • It translates IGMP joins from receivers into BGP updates sent to neighboring ASes.
    • It removes the need for an underlying unicast routing protocol for RPF checks.