200-301 Question 185
Single answerA network administrator is configuring inter-VLAN connectivity on a Layer 3 switch. The switch has three VLANs configured: VLAN 10, VLAN 20, and VLAN 30. The administrator creates the following configuration:
interface vlan 10 ip address 192.168.10.1 255.255.255.0 ! interface vlan 20 ip address 192.168.20.1 255.255.255.0 ! interface vlan 30 ip address 192.168.30.1 255.255.255.0 ! ip routing
After completing the configuration, devices in VLAN 10 cannot communicate with devices in VLAN 20 or VLAN 30. What is the most likely issue?
- A
The 'ip routing' command was not applied correctly.
- B
The switch ports are not assigned to the correct VLANs.
- C
The VLAN interfaces are in a shutdown state.
- D
The devices in the VLANs do not have the correct default gateway configured.
Show answer and explanation
Correct answer: B
Explanation
For inter-VLAN connectivity to work, the Layer 3 switch must have VLAN interfaces (SVIs) configured with IP addresses and routing enabled (as shown in the configuration). In addition, the switch ports must be assigned to the correct VLANs. If the switch ports are not associated with VLAN 10, 20, or 30, devices in those VLANs will not communicate even if the SVIs and routing are correctly configured. The most likely issue in this scenario is that the switch ports are not properly assigned to the VLANs.
- A. Incorrect.
The 'ip routing' command has been applied correctly, as it is present in the configuration. This is not the issue.
- B. Correct.
If switch ports are not assigned to the correct VLANs, devices will not be able to communicate because they will not belong to the intended VLANs. This is the most likely issue here.
- C. Incorrect.
If the VLAN interfaces were in a shutdown state, the configuration would explicitly show 'shutdown' under the interface settings. This is not mentioned in the scenario, so this is unlikely to be the issue.
- D. Incorrect.
While incorrect default gateway configuration on the devices would prevent inter-VLAN communication, this issue would need to be resolved on the devices themselves, not the switch. The scenario does not mention misconfigured default gateways.