Hello Miada,
low end access switches have limitations on the number of Vlans supported and also on the number of STP instances that can run at the same time. (to be noted these limits can be different in value).
If the total number of Vlans existing in your campus is greater then the switch limit the following happens:
- the switch reacts by moving from configured VTP client state to VTP transparent mode
- one or more vlans will be missing
I have seen this on a C2950 some years ago.
Typical limits are 64 or 128 vlans.
check with
show vtp status
show vlans
Hope to help
Giuseppe