Hi I posted a similar topic and performed some testing hopefully this will help?http://forums.veeam.com/vmware-vsphere-f24/exchange-dr-testing-t29262.html
Short answer is your Replicas will register with DNS their new IP address and everything will work.
If you do not have DNS servers at Site A DHCP will have to be changed to point at the ones on Site B (this then opens the question of do you have DHCP availaible at Site A if not DHCP Relay will be required to point at site B(Replica?))
Correct routing will be need in the above senario.
Hopefully I have understood what you are asking correctly?