350-401 Question 140
Single answerA company is configuring inter-VLAN routing on a Layer 3 switch to allow communication between VLAN 10 and VLAN 20. After configuring the VLAN interfaces and assigning IP addresses, users in VLAN 10 cannot communicate with users in VLAN 20. What is the most likely cause of the issue?
- A
The VLAN interfaces are not in an 'up/up' state.
- B
The switch does not have a default gateway configured.
- C
IP routing is not enabled on the Layer 3 switch.
- D
The devices in VLAN 10 and VLAN 20 are not using the correct subnet mask.
Show answer and explanation
Correct answer: C
Explanation
For inter-VLAN routing to work on a Layer 3 switch, IP routing must be enabled. Without IP routing, the switch cannot process packets and route them between VLANs, even if the VLAN interfaces and IP addressing are correctly configured.
- A. Incorrect.
If the VLAN interfaces are not in an 'up/up' state, they would not forward traffic, but the scenario assumes the interfaces are configured and active.
- B. Incorrect.
A default gateway configuration is not required for inter-VLAN routing on the Layer 3 switch itself. The issue described is specific to inter-VLAN communication.
- C. Correct.
If IP routing is not enabled on the Layer 3 switch, it cannot route traffic between VLANs, which would explain why communication between VLAN 10 and VLAN 20 is failing.
- D. Incorrect.
Incorrect subnet masks could cause routing issues, but the scenario does not suggest any misconfiguration of IP addressing.