If you have installed Direct Access on a domain controller you will find that you can't ping anything other than the DA server.
This is because DA needs port 53 which is the same port DNS listens on. As such you need to go into the DNS server properties and change from listen to all IP to bind to only selected IP's. Here you can select all apart from the one ending 3333:1 and the IPv6 looking one with the IPv4 on the end. Once you have completed this, restart and all should work.
Please do not comment about DA and DC on the same box this is just how to fix this issue if you have decided to setup in this way.