This is my setup: XP <--wireless -- Router_1 --wireless --> 2003_A 2003_B <--CAT5-- Router_1 On the Router_1, Cisco, WRT160Nv2: DHCP disabled, no static DNS 2003_A has DC, DHCP server, DNS server, File Server Before setting up DHCP server and DNS server, on 2003_A, it had IP: 192.168.1.103 After setting up DHCP server, IP and DNS server static on 2003_A: DHCP Enabled. . . . . . . . . . . : No IP Address. . . . . . . . . . . . : 192.168.1.2 Subnet Mask . . . . . . . . . . . : 255.255.255.0 Default Gateway . . . . . . . . . : 192.168.1.1 DNS Servers . . . . . . . . . . . : 192.168.1.2 Reverse lookup zone 192.168.1.x --> Status Running On 2003_A, I ran 'ipconfig /registerdns' ========================= XP & 2003_B can't join domain, error said wrong domain name, but ofcourse it's correct. XP and 2003_B show 2003_B - DHCP Enabled. . . . . . . . . . . : No IP Address. . . . . . . . . . . . : 192.168.1.11 Subnet Mask . . . . . . . . . . . : 255.255.255.0 Default Gateway . . . . . . . . . : 192.168.1.1 DNS Servers . . . . . . . . . . . : 68.87.85.102 Windows XP - Wireless DHCP Enabled. . . . . . . . . . . : Yes Autoconfiguration Enabled. . . : Yes IP Address. . . . . . . . . . . . : 192.168.1.102 Subnet Mask . . . . . . . . . . . : 255.255.255.0 Default Gateway . . . . . . . . . : 192.168.1.1 DNS Servers . . . . . . . . . . . : 192.168.1.103 How can I make XP and 2003_B to join the domain? Thanks so much in advance.

b and xp dns entries need to be at .2 not 68.87.85.102 and 192.168.1.103

I figured out that my Forward Lookup Zone in the DNS server was not set up correctly. After that it worked. Thanks.

If you say so. Unless you corrected what dns server the two were pointing to no changes in the ms dns server would make any difference.