Sadly this method does not allow for using an arbitrary nameserver.
If you need to make a request using a specific DNS server, you'll need to use either Pear/Net_DNS2, or libdns ( https://github.com/DaveRandom/LibDNS ).
If you want something shorter and lighter, you can also use this 150 lines function: https://gist.github.com/bohwaz/ddc61c4f7e031c3221a89981e70b830c