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Show vlan brief

As explained in Acing the CCNA Exam: Volume 1 Fundamentals and Protocols

show vlan brief is a Cisco IOS command that displays configured VLANs, their status, and their assigned switch ports.

show vlan brief displays a switch’s VLAN database, including VLAN IDs, names, status, and assigned ports. It is a quick way to verify VLAN configuration and identify the default placement of ports. section 12.2.1 section 12.5

SW1# show vlan brief                                                         #1
VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Gi0/0, Gi0/1, Gi0/2, Gi0/3   #2
                                                Gi1/0, Gi1/1, Gi1/2, Gi1/3   #2
                                                Gi2/0, Gi2/1, Gi2/2, Gi2/3   #2
1002 fddi-default                     act/unsup                              #3
1003 token-ring-default               act/unsup                              #3
1004 fddinet-default                  act/unsup                              #3
1005 trnet-default                    act/unsup                              #3
#1 Views SW1’s VLAN database
#2 All ports are in VLAN 1 by default.
#3 VLANs 1002–1005 also exist by default.

The output shows VLAN 1 with all ports by default, while VLANs 1002–1005 appear as reserved legacy VLANs with act/unsup status. section 12.2.1

Verify created and disabled VLANs

After creating VLANs 10, 20, and 30, show vlan brief lists their names and active status. After shutdown is applied to VLAN 10, its status appears as act/lshut, indicating a locally disabled VLAN. section 12.2.1 section 12.2.1

How Acing the CCNA Exam: Volume 1 Fundamentals and Protocols covers it

How deep it goes
Explains representative output and status values, but does not descend into VLAN tagging or trunk operation.
Examples
Uses default SW1 output, created Engineering, HR, and Sales VLANs, and a locally shut down VLAN 10.
What you can do after
Diagnose VLAN configuration by checking existence, names, status, and switch-port membership from the CLI.
How it connects
Connects VLAN verification with VLAN creation, VLAN naming, access ports, trunk ports, and network segmentation.
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