Default VLAN

Definition

• Default VLAN is the VLAN (VLAN 1 on Cisco switches) where all switch ports belong when the switch is new.
• Its role is to provide immediate connectivity before any VLAN configuration.

What Problem It Solves

• It lets a new switch work immediately without requiring VLAN setup.

What Happens If Not Used

Every new switch would require manual VLAN configuration before devices could communicate.

Easy Wording

The Default VLAN is the starting VLAN that every new switch uses.

Layman Example

• A new apartment building initially gives every resident the same entrance until separate entrances are assigned.

Technical Example

• A new switch is installed.
• PCs connect to access ports.
• All ports are in VLAN 1 by default.
• The administrator later moves Finance PCs to VLAN 10 and HR PCs to VLAN 20.

Limitation: Keeping everyone in VLAN 1 reduces network isolation. The solution is to create separate VLANs and assign ports appropriately.