VRRP will The router will start a pruning timer for the pruned downstream interface, and the interface will resume forwarding after the timer expires. How many seconds is this timer by default?

Question

Options

• A210 seconds
• B180 seconds
• C300 seconds
• D150 seconds

• A
  74% (26)
• B
  3% (1)
• C
  14% (5)
• D
  9% (3)

Explanation

Option A (210 seconds) is correct because in PIM Dense Mode (PIM-DM), when a router prunes a downstream interface, the upstream router starts a prune timer defaulting to 210 seconds; once this timer expires, the interface transitions back to the forwarding state and multicast traffic resumes flooding. Note: the question prefix referencing "VRRP" appears to be a labeling error - this concept belongs to PIM-DM multicast pruning behavior.

Why the distractors are wrong:

• B (180 seconds): This is a plausible-sounding round number but is not the defined default; it's often confused with other PIM or OSPF timer values.
• C (300 seconds): 300 seconds (5 minutes) is associated with other PIM timers (e.g., neighbor hold-down intervals), not the prune timer.
• D (150 seconds): Not a standard PIM-DM prune timer value; may be confused with half-life values in route flap dampening.

Memory tip: Think "2-1-0 prune" - 210 seconds is 3.5 minutes, and you can remember it as slightly less than a 4-minute round number, distinguishing it from the 300-second (5-minute) neighbor timers. If you remember PIM-DM prunes last 3½ minutes, option A is unmistakable.

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