demote domain controller

Hello, I have three domain controllers and I want to demote teh pdc. On the PDC I have also DNS installed. The other has dns and dhcp and the other MS- Exchange.I want to transfer the Active directory on the MS exchange server. I have selected it as a global catalog also. Have I to install DNS on the exchange server also.

thanks in advance

You are not required to have DNS installed on a DC or Exchange box. As long as they can communicate with a properly configured, local DNS server. Just use the server running DNS and DHCP.

Good luck. It sounds like you have your work cut out for you.