I created a AD on windows server 2008 r2 (in Extra Small). So I did as per this tutorial http://www.windowsazure.com/en-us/manage/services/networking/active-directory-forest/ using powershell.
It did not tell to create DNS server(on windows server), but I have it created in virtual network.
So the question is-
1) what's this all about?
2) what are the advantages and disadvantages?
3) Does it cost for me?