[monkkey]

У Вас контроллер домена с двумя (или более) сетевыми картами? Тогда сделайте правильную привязку DNS.

[XXXandr]

Да, имеется 2 сетевые карты.
Windows IP Configuration

Host Name . . . . . . . . . . . . : mainserver
Primary Dns Suffix . . . . . . . : firma.local
Node Type . . . . . . . . . . . . : Unknown
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
DNS Suffix Search List. . . . . . : firma.local

Ethernet adapter Local Area Connection 2:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Intel(R) PRO/1000 EB Network
ith I/O Acceleration #2
Physical Address. . . . . . . . . : 01-15-17-5F-ED-51
DHCP Enabled. . . . . . . . . . . : No
IP Address. . . . . . . . . . . . : 192.168.0.100
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.0.1
DNS Servers . . . . . . . . . . . : 192.168.0.100
192.168.0.1

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Intel(R) PRO/1000 EB Network
ith I/O Acceleration
Physical Address. . . . . . . . . : 01-15-17-5F-ED-50
DHCP Enabled. . . . . . . . . . . : No
IP Address. . . . . . . . . . . . : 192.168.1.1
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . :
DNS Servers . . . . . . . . . . . : 192.168.1.2
192.168.1.1

C:\Documents and Settings\Administrator>nslookup mainserver
Server: mainserver.firma.local
Address: 192.168.0.100

Name: mainserver.firma.local
Addresses: 192.168.0.100, 192.168.1.1

C:\Documents and Settings\Administrator>nslookup 192.168.1.1
Server: mainserver.firma.local
Address: 192.168.0.100

Name: mainserver.firma.local
Address: 192.168.1.1

C:\Documents and Settings\Administrator>nslookup 192.168.1.1
Server: mainserver.firma.local
Address: 192.168.0.100

Name: mainserver.firma.local
Address: 192.168.1.1

Не подскажете, что именно я пропустил.
Еще имеется вторичный dns сервер "server" 192.168.1.2 и 192.168.0.101