Cisco Certified Network Professional 2025 – 400 Free Practice Questions to Pass the Exam

In Rapid Spanning Tree Protocol (RSTP), the mechanism for detecting switch failures is primarily based on the exchange of Bridge Protocol Data Units (BPDUs). If a bridge does not receive an RSTP BPDU from a neighboring switch within the specified maximum age timeframe, it realizes that there may be a failure in the switch. The default time for switching failure detection in RSTP is indeed 6 seconds.

This time is derived from the parameter known as the "hello time," which is set to 2 seconds for RSTP. When a switch does not receive BPDUs from its neighbor for 3 consecutive hello periods, which takes 6 seconds (2 seconds per hello period multiplied by 3), it assumes that the neighboring switch has failed. This rapid detection capability is a key improvement RSTP has over the older Spanning Tree Protocol (STP), which could take significantly longer to react to network topology changes.

The values for the other choices do not correspond to the standard operating parameters of RSTP regarding failure detection, as they either exceed the defined period or do not align with the protocol's configuration for health checks and neighbor detection actions. Thus, recognizing the timing associated with RSTP’s hello time and its