CCNP Practice Question: Examine the following configuration snippet:…

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  The port will immediately transition to forwarding state and will be error-disabled if a BPDU is received.

  Why this is correct

  With PortFast configured on an access port, the switch port bypasses the normal Spanning Tree Protocol (STP) listening and learning states and transitions directly to forwarding, allowing endpoints such as PCs or IP phones to come up immediately. When BPDU Guard is also enabled (as is typical for access ports), the arrival of any Bridge Protocol Data Unit—which would indicate another switch has been connected—triggers an immediate error-disable of the port, preventing potential Layer 2 loops. This behavior is deterministic: forwarding first, then shutdown on any unexpected BPDU.

• ✗

  The port will remain in blocking state until a BPDU is received from the root bridge.

  Why it's wrong here

  This is incorrect because PortFast fundamentally overrides the STP state machine that would normally hold a port in the blocking state while it waits to determine the root bridge and listen for BPDUs. On a PortFast-enabled port, STP convergence is skipped entirely, so the port never enters blocking or listening; it moves straight to forwarding within milliseconds. Furthermore, if a BPDU from a root bridge or any switch were actually received, BPDU Guard would not keep the port in blocking—it would error-disable the port immediately, which is a different outcome than remaining in a stable STP state.

• ✗

  The port will only forward BPDUs and will not forward data traffic.

  Why it's wrong here

  This is wrong because a PortFast access port is designed to forward data traffic immediately, not merely to process spanning-tree BPDUs. In normal STP operation, a designated port in the forwarding state both sends and receives BPDUs while also forwarding user data frames; PortFast does not change this—it simply accelerates the transition to forwarding. If a BPDU arrives, BPDU Guard does not respond by just letting the port forward BPDUs; it shuts the port down entirely, placing it in the error-disabled state, so the port stops forwarding both data and BPDUs.

• ✗

  The port will participate in RSTP and will not be affected by BPDU reception.

  Why it's wrong here

  This option misrepresents how PortFast and BPDU Guard interact with RSTP or any STP variant. PortFast is an administrative override that puts the port into forwarding state immediately, regardless of whether the switch is running classic 802.1D, PVST+, or Rapid PVST+ (RSTP); it does not make the port a passive participant. BPDU Guard is equally agnostic to the STP variant—if any BPDU is received on a BPDU Guard-protected port, the port is error-disabled, not left unaffected. Therefore, the premise that RSTP participation somehow exempts the port from BPDU reactions is false.