For security purposes, which VLAN is recommended to be set as the native VLAN?

Setting the native VLAN as an unused VLAN is considered a security best practice in network design. The native VLAN is the VLAN that is assigned to untagged traffic on a trunk port. By designating an unused VLAN as the native VLAN, you minimize the risk of unauthorized access or potential attacks. If an unused VLAN is set as the native VLAN, any untagged traffic that inadvertently arrives on a trunk link is dropped or ignored, as this VLAN does not have any interfaces assigned to it, thus enhancing the security of the network.

On the other hand, setting the native VLAN to the default VLAN or an active VLAN could lead to security vulnerabilities. For example, the default VLAN (often VLAN 1) is commonly used in many network setups, making it a target for attackers seeking to exploit known configurations. Assigning an active VLAN as the native VLAN may expose sensitive traffic or allow unauthorized access if proper segmentation and policies are not in place.

Therefore, utilizing an unused VLAN for this purpose provides an additional layer of security by ensuring that any unexpected or unauthorized traffic does not interfere with active VLANs used for legitimate purposes.