Github just added AWS DNS:

github.com:

    Name Server: ns2.p16.dynect.net
    Name Server: ns-1283.awsdns-32.org.
    Name Server: ns-1707.awsdns-21.co.uk.
    Name Server: ns-421.awsdns-52.com.
    Name Server: ns1.p16.dynect.net
    Name Server: ns4.p16.dynect.net
    Name Server: ns3.p16.dynect.net
    Name Server: ns-520.awsdns-01.net.