200-301 Question 228
Select 2A network engineer is tasked with ensuring that unauthorized switches cannot become the root bridge in the network while also preventing accidental topology loops on unused ports. What combination of Spanning Tree Protocol (STP) features should be implemented on the corresponding switch interfaces to achieve this?
- A
Enable Root Guard on interfaces connected to other switches
- B
Enable BPDU Guard on edge ports configured with PortFast
- C
Enable Loop Guard on all access ports
- D
Enable BPDU Filter on all trunk ports connected to other switches
- E
Enable Root Guard on access ports connected to end devices
Show answer and explanation
Correct answers: A, B
Explanation
To prevent unauthorized switches from becoming the root bridge, Root Guard should be configured on interfaces connected to other switches. Additionally, BPDU Guard should be applied to edge ports (configured with PortFast) to ensure that no BPDUs are received on these ports, protecting the STP topology from misconfigurations or rogue devices. These two features work together to enhance the stability and security of the STP environment.
- A. Correct.
Root Guard should be enabled on interfaces connected to other switches to prevent unauthorized switches from becoming the root bridge.
- B. Correct.
BPDU Guard should be enabled on edge ports configured with PortFast to shut down the port if a BPDU is received, preventing unauthorized devices from affecting the STP topology.
- C. Incorrect.
Loop Guard is typically used on non-designated ports in the STP topology to prevent loops caused by unidirectional link failures, but it is not relevant for access ports in this scenario.
- D. Incorrect.
BPDU Filter suppresses BPDU traffic on configured interfaces, which can lead to misconfigurations and is not suitable for trunk ports connected to other switches.
- E. Incorrect.
Root Guard is not intended for access ports connected to end devices, as end devices do not participate in STP and cannot become the root bridge.