CCNA: Cisco Certified Network Associate — Question 356

What occurs when PortFast is enabled on an interface that is connected to another switch?

Answer options

• A. Root port choice and spanning-tree recalculation are accelerated when a switch link goes down.
• B. After spanning-tree converges, PortFast shuts down any port that receives BPDUs.
• C. VTP is allowed to propagate VLAN configuration information from switch to switch automatically.
• D. Spanning-tree fails to detect a switching loop increasing the likelihood of broadcast storms.

Correct answer: D

Explanation

When PortFast is enabled on a switch interface connected to another switch, it can prevent the spanning-tree protocol from detecting switching loops. This oversight can lead to a higher chance of broadcast storms, as the network may not effectively manage loops. The other options describe behaviors that do not accurately represent the implications of enabling PortFast.