1) Do the Initial configuration of F5 BIG IP DNS such as Listner, DNS Profile and Self IP's.
2) Use the different IP address on the F5 BIG IP DNS Server compared to the existing DNS Server
3) Perform the Zone transfer between Existing DNS Server and F5 BIG IP DNS Server ( F5 BIG IP DNS Server is acting as Secondary Authoritative DNS Server)
4) Disable the self IP address on the F5 BIG IP DNS Server
5) Make the F5 BIG IP DNS Server ( Secondary Authoritative DNS Server) as the same IP address as Existing Authoritative DNS Server
6) Decommission Existing DNS Server and Enable the self IP address on the F5 BIG IP DNS Server
Best Regards,
Kareem