200-301 Question 27
Single answerA network administrator is troubleshooting a connectivity issue between two endpoints on a corporate network. PC1, located in VLAN 10, cannot communicate with PC2, located in VLAN 20. Both PCs are connected to the same switch, and the switch interfaces are configured correctly. The administrator realizes the issue might be caused by a missing configuration at the Layer 3 device. Which configuration change must be implemented to resolve the issue?
- A
Enable inter-VLAN routing on the Layer 3 device by configuring sub-interfaces for VLAN 10 and VLAN 20.
- B
Assign both endpoints to the same VLAN within the Layer 2 switch.
- C
Configure a trunk port between the Layer 3 device and the switch to allow traffic between VLANs.
- D
Enable spanning tree protocol (STP) to ensure proper path selection between the devices.
Show answer and explanation
Correct answer: A
Explanation
To enable communication between endpoints in different VLANs (VLAN 10 and VLAN 20), inter-VLAN routing must be configured on the Layer 3 device. This is typically done by creating sub-interfaces for each VLAN and assigning appropriate IP addresses to allow routing between the VLANs. Other options either address unrelated issues or bypass the intended VLAN separation.
- A. Correct.
Correct. Inter-VLAN routing is required for communication between devices in different VLANs. Configuring sub-interfaces for VLAN 10 and VLAN 20 on the Layer 3 device enables this functionality.
- B. Incorrect.
Incorrect. Assigning both endpoints to the same VLAN would allow communication, but it bypasses the need for inter-VLAN routing and doesn't resolve the issue as described in the scenario.
- C. Incorrect.
Incorrect. Configuring a trunk port allows multiple VLANs to pass traffic between the switch and the Layer 3 device, but it does not enable inter-VLAN communication on its own.
- D. Incorrect.
Incorrect. Spanning Tree Protocol (STP) is used to prevent loops in the Layer 2 topology and does not address the inter-VLAN routing issue described.