What is the default VLAN interface often referred to?

The default VLAN interface is commonly referred to as VLAN 1. In Cisco networking, VLAN 1 is automatically created upon setting up a switch and is used for management purposes. This VLAN is typically the default VLAN assigned to all switch ports that have not been explicitly assigned to another VLAN, making it essential for various management activities, such as accessing the switch through a management interface.

Using VLAN 1 allows for the default behavior in many switching environments. It's also important to note that the default settings for many network configurations utilize VLAN 1 unless specified otherwise, validifying its significance.

The other VLAN options listed—like VLAN 0, VLAN 100, and VLAN 10—are either custom configurations or not predefined as default within networking equipment. VLAN 0 is an invalid configuration for user VLANs, as it is reserved for specific functions, and establishing custom VLANs like 100 or 10 would necessitate further manual configuration to convert ports or set management access, which does not apply directly to the default state of a typical switch setup.