easyMultiple ChoiceObjective-mapped

200-901 Practice Question: Refer to the exhibit

Exhibit

Refer to the exhibit.
```
interface GigabitEthernet1/0/1
 description CONNECTION TO APP SERVER
 switchport access vlan 10
 switchport mode access
 spanning-tree portfast
 spanning-tree bpduguard enable
```

Refer to the exhibit. An engineer applied this configuration to a Cisco switch port connected to an application server. The server runs a critical business application that should not be disrupted. However, after applying the configuration, the port goes into errdisable state. What is the most likely cause?

⚠ Common exam trap

Cisco often tests the misconception that BPDU guard is only for trunk ports or that PortFast is incompatible with access ports, but the trap here is that candidates overlook how a server can generate BPDU frames (e.g., from a virtual switch or bridging software) and that BPDU guard on an access port will errdisable it.

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

The server is generating BPDU frames, triggering BPDU guard.

BPDU guard is enabled on the switch port (implicitly or explicitly via spanning-tree bpduguard enable). When the application server sends BPDU frames—perhaps because it is running a software bridge, virtualization host, or has a misconfigured NIC—the switch detects these frames on a port configured with portfast and immediately errdisables the port to prevent a potential bridging loop. This matches the symptom of the port going into errdisable state after applying the configuration.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
The VLAN 10 does not exist on the switch.
Why it's wrong here
A missing VLAN would result in the port being inactive, not errdisable.
✗
The spanning-tree portfast command is incompatible with access ports.
Why it's wrong here
Portfast is typically used on access ports to speed up transition to forwarding state; it does not cause errdisable.
✗
The switchport mode access command is incorrect for a server connection.
Why it's wrong here
Access mode is appropriate for connecting a single server.
✓
The server is generating BPDU frames, triggering BPDU guard.
Why this is correct
BPDU guard errdisables a port if it receives a BPDU, which can happen if the server runs STP or is connected to another switch.

Visual reference

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200-901 Practice Question: Refer to the exhibit

Exhibit

Why each option matters

Option-by-option breakdown

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