350-401 Question 136
Select 3A network administrator is tasked with configuring a switch to prevent a rogue device from becoming the root bridge in a Rapid Spanning Tree Protocol (RSTP) topology. Additionally, the administrator wants to ensure that no end-user devices can inject BPDU packets into the network, potentially disrupting the topology. Which combination of features should the administrator enable on the switch ports?
- A
Enable BPDU Guard on all edge ports connected to end-user devices
- B
Enable Root Guard on all trunk ports connecting to other switches
- C
Enable Root Guard on all edge ports connected to end-user devices
- D
Enable BPDU Filter on all trunk ports connecting to other switches
- E
Enable PortFast on all edge ports connected to end-user devices
- F
Enable BPDU Guard on all trunk ports connecting to other switches
Show answer and explanation
Correct answers: A, B, E
Explanation
To protect the Spanning Tree topology and prevent disruptions, the administrator needs to enable BPDU Guard on edge ports to disable them if BPDUs are received, Root Guard on trunk ports to prevent any connected switches from becoming the root bridge, and PortFast on edge ports to optimize convergence for end-user devices. These configurations together enhance the security and efficiency of the STP implementation.
- A. Correct.
Correct: Enabling BPDU Guard on edge ports ensures that if any BPDUs are received (indicating a potential misconfiguration or attack), the port will be disabled to protect the network topology.
- B. Correct.
Correct: Enabling Root Guard on trunk ports prevents connected switches from advertising themselves as the root bridge, protecting the network from rogue switches.
- C. Incorrect.
Incorrect: Root Guard is not meant for edge ports connected to end-user devices, as these ports should not participate in STP.
- D. Incorrect.
Incorrect: BPDU Filter suppresses sending or receiving of BPDUs, which is not recommended on trunk ports as it can disrupt STP functionality.
- E. Correct.
Correct: Enabling PortFast on edge ports allows them to bypass the STP listening and learning states, reducing convergence time for end-user devices.
- F. Incorrect.
Incorrect: BPDU Guard is not recommended on trunk ports, as they are typically used for inter-switch connections and need to process BPDUs for STP operations.