nslookup timed out for mx records only - Windows 2008 R2 only

Hello Guys,

We are using Windows 2008 R2 as the DNS server and now we would like to make the mx query by using nslookup for the external mail servers (like mail.exchange.com). The forwarders will use the external DNS server (like google 8.8.8.8). If we use 8.8.8.8 as the DNS server, mail.exchange.com can be resolved. However, if we use back the DC DNS server, it will say.

Server:  domain1.org
Address:  192.168.1.1

DNS request timed out.
    timeout was 2 seconds.
*** Request to domain1.org timed-out

In the meantime, I did setup Windows 2003 DNS server an there have no issues when performing the nslookup. It means that there have some configuration need to be configured for Windows 2008 R2 DNS server.