Hyper-V Machine cannot join domain

Hyper-V Machine cannot join domain

I have a laptop which has Hyper-V installed.
I have two virtual machines, "ws12-dc", the domain controller (domain:
idg.local), and ws12-sql12, the sql server 2012 machine.
When I try to join the domain on my second machine, it say's that
"idg.local" cannot be found. I can ping the ws12-dc by it's ip address,
but I cannot ping it using "ws12-dc", nor can I ping "idg.local".
I tried to do a ipconfig /flushdns then ipconfig /registerdns.