The commands used on the CLI of the switch to verify and debug VLANS are :

Command	Commentary
show vlan	It shows us all informations about existing VLANS.
show vlan brief	It shows us the informations in brief.
show vlan id (identification number)	Example : show vlan id 2, displays informations about VLAN 2
show vlan (name of the vlan)	Example : show vlan STUDENTS, displays informations about a VLAN named STUDENTS.
show interfaces switchport	It displays the status of all ports of a switch.
delete flash:vlan.dat	It erases the database of all VLANS except : 1,1002 (fddi), 1003 (token-ring), 1004 (fddinet) and 1005 (trnet)