200-301 Question 183
Single answerA network administrator is configuring InterVLAN routing on a Layer 3 switch. VLAN 10 (192.168.10.0/24) and VLAN 20 (192.168.20.0/24) are configured. The administrator enables IP routing and assigns the following interface configurations:
- Interface VLAN 10: IP address 192.168.10.1/24
- Interface VLAN 20: IP address 192.168.20.1/24
After completing the configuration, devices in VLAN 10 cannot communicate with devices in VLAN 20. What could be the cause of the issue?
- A
The Layer 3 switch is missing the 'ip routing' command.
- B
The devices in VLAN 10 and VLAN 20 do not have the default gateway configured.
- C
The VLANs are not assigned to switchports on the Layer 3 switch.
- D
An access control list (ACL) is blocking traffic between VLANs.
Show answer and explanation
Correct answer: B
Explanation
For inter-VLAN communication, devices in each VLAN must have their default gateway set to the IP address of the respective VLAN interface on the Layer 3 switch (192.168.10.1 for VLAN 10 and 192.168.20.1 for VLAN 20). Without this configuration, devices cannot route traffic beyond their own VLAN, which explains why communication is not working in this scenario.
- A. Incorrect.
The 'ip routing' command is already enabled, as mentioned in the scenario. This is not the issue.
- B. Correct.
If the devices in VLAN 10 and VLAN 20 do not have their default gateways configured as 192.168.10.1 and 192.168.20.1 respectively, they will not be able to communicate across VLANs, even if inter-VLAN routing is configured correctly.
- C. Incorrect.
The scenario assumes that VLANs are already assigned to the appropriate switchports, so this is not likely the cause.
- D. Incorrect.
While an ACL could block inter-VLAN communication, there is no mention of ACLs being configured in the scenario.