In HSRP, how do interface determine failure and assign standby and active routers?

Question

Options

• Aby using Cisco Discovery
• Bby using Cisco Spanning Tree protocol
• Cby exchanging BPDUs
• Dby using multicast UDP hello messages

• A
  2% (1)
• B
  6% (3)
• C
  2% (1)
• D
  90% (45)

Explanation

HSRP (Hot Standby Router Protocol) routers in the same group communicate by exchanging Hello messages sent to a well-known multicast address (224.0.0.2 for HSRPv1, 224.0.0.102 for HSRPv2) using UDP. The active router sends these hellos at a configurable hello interval (default 3 seconds). If the standby router does not receive a hello within the hold time (default 10 seconds), it concludes the active router has failed and transitions itself to the active role. CDP (A) is a Cisco discovery protocol used to identify neighboring devices - it plays no role in HSRP failover. Spanning Tree (B) and BPDUs (C) are Layer 2 loop-prevention mechanisms and are completely unrelated to HSRP gateway redundancy.

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