STP STP Fundamentals 2 — Questions and Answers
Question 1: What is a designated port in STP?
- A port on each segment that provides the best path to the root bridge and forwards traffic (Correct answer)
- A port that is always blocked
- A port connected to end devices only
- A management port
Correct answer: A port on each segment that provides the best path to the root bridge and forwards traffic
Each network segment has one designated port that forwards traffic, determined by having the lowest cost path to the root bridge.
Question 2: What is an STP root port?
- The port on each non-root switch that has the lowest cost path to the root bridge (Correct answer)
- A port on the root bridge
- A port that is always in blocking state
- A port used for management access
Correct answer: The port on each non-root switch that has the lowest cost path to the root bridge
Each non-root switch selects one root port, which is the port with the best path (lowest cost) to the root bridge.
Question 3: What causes an STP topology change?
- A port transitioning to or from the forwarding state (Correct answer)
- A new VLAN being created
- A change in IP addresses
- A DNS server update
Correct answer: A port transitioning to or from the forwarding state
Topology changes occur when ports change state, triggering the network to update its forwarding information.
Question 4: What is the STP max age timer?
- The maximum time a switch stores BPDU information before discarding it, default 20 seconds (Correct answer)
- The maximum age of a switch
- The maximum uptime allowed
- The maximum number of VLANs
Correct answer: The maximum time a switch stores BPDU information before discarding it, default 20 seconds
If a switch does not receive a BPDU within the max age period, it assumes a topology change and begins recalculating.
Question 5: What is the convergence time for 802.1D STP?
- 30 to 50 seconds typically (Correct answer)
- Less than 1 second
- 5 minutes
- 10 minutes
Correct answer: 30 to 50 seconds typically
Traditional 802.1D STP can take 30-50 seconds to converge after a topology change as ports transition through states.
Question 6: What is a BPDU guard?
- A feature that disables a port if it receives a BPDU, protecting against unauthorized switches (Correct answer)
- A physical lock on a switch port
- Firewall protection
- Password protection for BPDUs
Correct answer: A feature that disables a port if it receives a BPDU, protecting against unauthorized switches
BPDU guard protects the network by shutting down ports that should not be receiving BPDUs, such as ports connected to end devices.
STP STP Fundamentals 2
What is a designated port in STP?