acecombat wrote:a transparent authentication proxy, but I don't think the problem is with that as the error doesnt mention a proxy, rather it cannot find the address
Are you sure? It's not that it can't find and address, it's that it can't resolve an address (or host, rather).
Have you tried pinging (e.g. from a DOS prompt) www.abc.net.au from the computer PHP is running on? There is something that's preventing PHP from resolving www.abc.net.au to an IP address (namely 80.12.96.57 at present). You might try a TCP monitoring program such as Wireshark to monitor the TCP connections made by PHP and get an idea of what's happening.