350-401 Question #304: Real Exam Question with Answer & Explanation

Question

Which two statements about PIM snooping are true? (Choose two)

Options

• AIt floods join and prune messages on all router ports.
• BIt requires designated forwarder election messages.
• CWhen PIM snooping is enabled, the switch allows all multicast packets for each IP multicast
• DIt requires RGMP to be enabled on the VLAN.
• EIt requires IGMP snooping to be enabled on the switch.
• FThe ip pirn snooping command is an interface-level command.

Explanation

PIM snooping helps optimize multicast traffic forwarding on Layer 2 switches by processing PIM control messages and often requires IGMP snooping to be enabled for comprehensive multicast management.

Common mistakes.

• A. PIM snooping's primary goal is to prevent flooding of PIM control messages by forwarding them only to relevant router ports, not to flood them on all router ports.
• C. PIM snooping focuses on PIM control messages, not on allowing or disallowing all multicast data packets. Multicast data forwarding is managed by IGMP snooping's understanding of receiver memberships.
• D. RGMP (Router-port Group Management Protocol) is an alternative to PIM snooping for router port discovery and is not a prerequisite for PIM snooping.
• F. PIM snooping is typically configured globally or on a per-VLAN basis, not on individual interfaces.

Concept tested. PIM snooping functionality and dependencies

Reference. https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst9300/software/release/16_12/configuration_guide/ip_mcast/b_1612_ip_mcast_9300_cg/configuring_igmp_snooping_and_pim_snooping.html

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