350-401 · Question #567
350-401 Question #567: Real Exam Question with Answer & Explanation
The correct answer is D: Designated routers receive traffic only from groups through which a join message is received.. When PIM snooping is enabled, designated routers only receive multicast traffic for groups that have active join messages, preventing unnecessary flooding of traffic to all routers.
Question
Which statement about traffic management when PIM snooping is enabled is true?
Options
- ATraffic is restricted to host ports.
- BAll multicast traffic is flooded to the designated router.
- CJoin message are flooded to all routers.
- DDesignated routers receive traffic only from groups through which a join message is received.
Explanation
When PIM snooping is enabled, designated routers only receive multicast traffic for groups that have active join messages, preventing unnecessary flooding of traffic to all routers.
Common mistakes.
- A. PIM snooping aims to restrict traffic to interested parties, but 'host ports' is too narrow; it applies to router ports as well, and often works in conjunction with IGMP snooping for host ports.
- B. PIM snooping specifically aims to prevent all multicast traffic from being flooded to designated routers; instead, it intelligently forwards traffic based on membership.
- C. PIM Join messages are typically sent upstream towards the RP or source and are not flooded to all routers by PIM snooping; PIM snooping inspects these messages to build forwarding tables.
Concept tested. PIM snooping traffic optimization
Reference. https://www.cisco.com/c/en/us/td/docs/ios/ipmulticast/configuration/guide/imc_pmsg.html
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