What is VTP?
VTP is a Cisco Proprietary Layer 2 protoco; that allows switches to get and send VLAN info. You can create VLAN’s in one Switch and send it over to the rest of the switches via VTP. To do this, VTP carries VLAN information to all the switches in a VTP domain. VTP advertisements can be sent over 802.1Q, and ISL trunks.
Advantages of VTP:
It reduces administrative overhead like suppose you have 100 switches in your network and you want to create a new VLAN without VTP, you need to login to 100 switches and create the VLAN whereas with VTP you only need to create VLAN in your VTP server.
Disadvantages of VTP:
VTP can be devastating as well. Suppose your network VTP server is having a revision number of 10. Now you have a switch failure in your network which you are replacing with your LAB switch which belongs to same VTP domain of your network with a higher revision number than your VTP server and having different VLAN.