We have an external web url which will come on our frontend f5 VIP but server is responding to the external passing the F5, needs to route back to F5

Domain masking:

when HTTP_REQUEST {
if { [HTTP::host] contains "abcd.com" } {
HTTP::host [string map {abcd.com xyz.com} [HTTP::host]] 
}

when HTTP_RESPONSE {
if { [HTTP::header values Location] contains "xyz.com" } {
HTTP::header replace Location [string map {xyz.com abcd.com} [HTTP::header value Location]]
}
}