Cisco CCNA Spanning Tree Protocol (STP) 2

Question 1

Which STP port state forwards data frames but does NOT learn MAC addresses?

Accepted Answer

Listening

Answer

The Listening state participates in frame forwarding decisions but does not populate the MAC address table.

Question 2

A switch has a bridge priority of 32768 and a MAC address of 00:1A:2B:3C:4D:5E. What is its Bridge ID?

Accepted Answer

32768:00:1A:2B:3C:4D:5E

Answer

The Bridge ID is a combination of the bridge priority (2 bytes) followed by the MAC address (6 bytes).

Question 3

What is the default STP forward delay timer value?

Accepted Answer

15 seconds

Answer

The default forward delay is 15 seconds, which applies to both the Listening and Learning states.

Question 4

Which type of STP port provides the best path from a non-root switch back toward the root bridge?

Accepted Answer

Root port

Answer

Each non-root switch has exactly one root port, which is the port with the lowest cost path to the root bridge.

Question 5

In PVST+, how is the extended system ID used in the bridge priority field?

Accepted Answer

The VLAN ID is added to the bridge priority

Answer

PVST+ uses the lower 12 bits of the 16-bit priority field as the extended system ID (VLAN ID), so valid priorities must be multiples of 4096.

Cisco CCNA Practice Test