STP Basics and Concepts 5

Question 1

Which command is used on a Cisco switch to manually set a switch as the root bridge using a specific priority?

Accepted Answer

spanning-tree vlan 1 priority 0

Answer

spanning-tree mode root primary

Answer

switchport spanning-tree priority 0

Answer

spanning-tree root-bridge vlan 1

Question 2

What STP feature prevents a port from transitioning to Forwarding if it stops receiving BPDUs from the designated switch?

Accepted Answer

Loop Guard

Answer

Root Guard

Answer

BPDU Filter

Answer

BPDU Guard

Question 3

What is the function of Root Guard in STP?

Accepted Answer

Prevents inferior BPDUs from causing a new root election on designated ports

Answer

Blocks all BPDUs on access ports

Answer

Forces a port into the root port role

Answer

Disables STP on uplink ports

Question 4

In which scenario would an STP alternate port transition to the Forwarding state?

Accepted Answer

When the root port on the same switch fails

Answer

When the hello timer expires

Answer

When a new VLAN is created

Answer

When the designated port sends a TCN

Question 5

What is the significance of a Bridge ID of 0 (priority 0) in STP?

Accepted Answer

The switch is guaranteed to become the root bridge

Answer

The switch is excluded from STP participation

Answer

The switch advertises maximum path cost

Answer

BPDUs from this switch are ignored

Question 6

Which type of BPDU does the root bridge send, and which type does a non-root switch send upstream when a topology changes?

Accepted Answer

Configuration BPDUs (root); TCN BPDUs (non-root)

Answer

TCN BPDUs (root); Configuration BPDUs (non-root)

Answer

RST BPDUs (root); TCN BPDUs (non-root)

Answer

Configuration BPDUs (root); RST BPDUs (non-root)

Question 7

What is the purpose of the STP BackboneFast feature (proprietary Cisco)?

Accepted Answer

Detects indirect link failures and immediately starts aging out the max age timer

Answer

Speeds up PortFast transitions on access ports

Answer

Converts STP to RSTP automatically

Answer

Enables rapid transition for trunk ports only