Changing the URL from the original VIP address to the Node's address

It's pretty straight forward. Add an empty STREAM profile to your VIP and this iRule:

when HTTP_REQUEST {
    STREAM::disable
    HTTP::header remove "Accept-Encoding"
}
when HTTP_RESPONSE {
    if { [HTTP::header value Content-Type] contains "text" } {
        STREAM::expression "@[/body]@[LB::server addr][/body]@"
        STREAM::enable
    }
}

The STREAM profile here will add the chosen server's IP address just before the end body tag of the document. You could extend this in a few ways:

1. The additional information is more or less pure HTML, so you could through it all into a hidden object or HTML comment.

2. You could do a reverse lookup of that IP to get the server name, and then do the above:

   when RULE_INIT  {
       set static::dns_server 10.80.0.200
   }
   when HTTP_REQUEST {
       STREAM::disable
       HTTP::header remove "Accept-Encoding"
   }
   when HTTP_RESPONSE {
       if { [HTTP::header value Content-Type] contains "text" } {
           set servername [RESOLV::lookup @$static::dns_server -ptr [LB::server addr]]
           STREAM::expression "@[/body]@$servername[/body]@"
           STREAM::enable
       }
   }