iRule URL Rewrite for Multiple domains

You could use a class along with the matchclass command (look in the wiki for an example on that one). Or you could use a switch statement if you want all the domains within your iRule and not externalized in a class

when HTTP_REQUEST {
  switch [HTTP::host] {
    "www.test.com" -
    "test.com" -
    "www.xyz.com" -
    "xyz.com" - {
      HTTP::redirect "http://primary.com[HTTP::uri]"
    }
  }
}

Remove the "[HTTP::uri]" from the redirect if you don't want to carry on the original request with the redirect.

If you have many addresses, it might be simpler to add them all to a class and use the matchclass command to search the class for the given host.

-Joe