ICND1 Spanning Tree Protocol (STP) 1

Question 1

What is the primary purpose of Spanning Tree Protocol (STP)?

Accepted Answer

To prevent switching loops in Layer 2 networks

Answer

STP prevents Layer 2 switching loops by placing redundant ports in a blocking state, stopping broadcast storms.

Question 2

Which IEEE standard defines the original Spanning Tree Protocol?

Accepted Answer

IEEE 802.1D

Answer

IEEE 802.1D defines the original STP specification; 802.1W defines RSTP and 802.1Q defines VLANs.

Question 3

What is the default bridge priority value used by Cisco switches in STP?

Accepted Answer

32768

Answer

Cisco switches default to a bridge priority of 32768, which is the midpoint of the valid range and must be a multiple of 4096.

Question 4

In STP, which port state actively forwards user traffic and learns MAC addresses?

Accepted Answer

Forwarding

Answer

Only the Forwarding state allows a port to send and receive data traffic; it is the final stable active state.

Question 5

How is the Root Bridge elected in an STP topology?

Accepted Answer

The switch with the lowest Bridge ID wins

Answer

The switch with the lowest Bridge ID (priority + MAC address) wins the Root Bridge election.

(ICND1) Interconnecting Cisco Networking Devices Part 1 Practice Test