What does VLAN stand for?
VLAN stands for Virtual Local Area Network. Splits one physical switch into separate logical networks, each its own broadcast domain, so traffic is isolated by department or device type without extra hardware. Traffic between VLANs needs a router or Layer 3 switch; 802.1Q tags carry several VLANs over a trunk.
A VLAN splits one physical switch into separate layer 2 networks. Devices in different VLANs do not see each other's broadcasts and need a router or layer 3 switch to communicate. Frames carry their VLAN number in an IEEE 802.1Q tag, a 12-bit field that allows VLAN IDs from 1 to 4094. A trunk port carries many VLANs between switches; an access port belongs to one.
VLAN in practice: an example
An office puts staff in VLAN 10, IP phones in VLAN 20 and guests in VLAN 30 on the same switches. Guests get internet access only, because the firewall rule between VLAN 30 and the others denies everything. Moving a desk to another floor only needs the port assigned to the same VLAN.
What VLAN is confused with
VLAN vs subnet: what is the difference?
A VLAN is a layer 2 separation on switches. A subnet is a layer 3 address range. They are usually paired one to one, but they are different things.
VLAN vs VXLAN: what is the difference?
VXLAN is an overlay used in data centres that carries layer 2 segments over an IP network and supports far more segments than the 4094 VLAN IDs. What VXLAN stands for
Which exams cover VLAN?
VLAN is on the official CompTIA acronym list for two of the four exams covered here.
- Network+ N10-009: 2.0 (Network Implementation); 4.0 (Network Security); 5.0 (Network Troubleshooting).
- A+ 220-1201 and 220-1202: 220-1201 2.0 (Networking). Listed there as “Virtual LAN [Local Area Network]”.
Each number is a CompTIA exam objective and the name in brackets is its domain. The exam puts the term in a scenario; it does not ask you to recite the expansion.
Check yourself: two practice questions
Written by CertSprint for this page. They are not taken from any exam.
1. Two PCs are on the same switch but in different VLANs. What is required for them to communicate?
- A crossover cable
- A router or layer 3 switch
- A second NIC in each PC
- Nothing, the switch forwards between VLANs
Show the answer
B. A router or layer 3 switch. Traffic between VLANs must be routed. A layer 2 switch keeps VLANs isolated.
2. Which port type carries traffic for several VLANs between two switches?
- Access port
- Trunk port
- Console port
- Mirror port
Show the answer
B. Trunk port. A trunk tags frames with their VLAN ID so one link can carry many VLANs.
Sources: IEEE 802.1Q: Bridges and Bridged Networks; NIST glossary: VLAN. The acronym and its expansion come from CompTIA's official acronym lists, linked from each exam glossary above. The explanation, example and questions are CertSprint's own, checked against these sources on 11 November 2026.