By default, the time interval for sending PIM Hello messages on the router interface is () seconds.

Question

Options

• A30
• B60
• C90
• D120

• A
  83% (45)
• B
  11% (6)
• C
  2% (1)
• D
  4% (2)

Explanation

PIM (Protocol Independent Multicast) Hello messages are sent at a default interval of 30 seconds, as defined in RFC 4601. Routers send these Hellos out PIM-enabled interfaces to discover neighbors and maintain adjacency; if a neighbor is not heard from within the Hold Time (typically 3.5x the Hello interval, or 105 seconds), it is considered down.

Options B (60), C (90), and D (120) are plausible distractors because they are multiples of 30 and resemble timer values from other protocols, but none of them match the PIM specification default. Candidates sometimes confuse this with OSPF or EIGRP timers, which use different defaults depending on network type.

Memory tip: Thirty seconds is the PIM Hello default -- think "30 for PIM, same as OSPF Dead on point-to-point links," or simply anchor it as the lowest option among the choices, since protocol designers favor shorter hello intervals to detect failures faster.

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