Creating DNS forwarding and/or Stub - Timeout error during validation

Hi,

I am trying to set up trust between two domains on different forests.  While creating stub zone on DOMAIN2 I receive "timeout error" whenever the master DNS of DOMAIN1 is being validated. The same is true if I create forwarder for DOMAIN1 on DOMAIN2.

Creating stub zone on DOMAIN1 for DOMAIN2 is successful. no validation errors 

DC's on both domains can ping each other. I can tracert from DOMAIN1 DC to DOMAIN2 DC and vice versa through the correct gateway. All firewall ports are set to allow trust including port 53 tcp and udp. I already have a trust with another domain on 3rd forest set up across the same firewall.

IPv6 is not enabled on the problem DC (Windows 2008)

Thanks in advance