Question

Which Cisco switch feature ensures that configured switch edge ports do not cause Layer 2 loops if a port is mistakenly connected to another switch?

a) Spanning Tree Protocol (STP)
b) PortFast
c) EtherChannel
d) VLAN Trunking Protocol (VTP)

Answer 1

The Cisco switch feature that prevents Layer 2 loops on edge ports connected to a single host is PortFast. It allows these ports to immediately transition to the forwarding state, bypassing normal STP delays.

Step-by-step explanation:

The feature in Cisco switches that ensures configured switch edge ports do not cause Layer 2 loops if a port is mistakenly connected to another switch is known as PortFast. This feature is used on ports connected to a single host to bypass the normal time-consuming transitions that Spanning Tree Protocol (STP) executes to prevent loops. By enabling PortFast on an access port, it directly transitions to the forwarding state, significantly reducing the time it takes for the port to begin passing traffic. However, caution is needed because if a switch is connected to a PortFast-enabled port, loops can occur since STP loop safeguards are not in place during the initial stages.