Hi All,I have using Windows Server 2008 Standard R1 as my domain controller with a new and stand alone domain forest.However, computers unable to join into the domain if I allow the computer to "Obtain an IP address automatically".I can only join the domain only if I fixed the computer IP address. The IP address that I key in, is actually same as the IP that the computer obtain based on "DHCP enable".After I join the computer into the domain, I try to change the IP setting to "Obtain an IP address automatically", I will unable to connect into the domain again.I have another device as DHCP to assign IP address to the computers based on computer's MAC address, so the computers will always obtain the same IP address.I have proceed same testing on Windows Server 2003, but the same issue did not happened.Can anyone help me on this? Why the computer can connect to the domain only if I fixed the IP address, although my DHCP is able function and assign IP address to the computers?Is it because of the Firewall setting or the policy setting that cause this issue?Is there any policy in the Group Policy that will check on the computer IP address before connect into domain?The computer OS that using is Windows 7 and Windows XP.Thanks.

Check your DHCP scope option and check twice ..whether or not you have provided the DNS server's address (should be you dc's IP) as DHCP scope option. Also make sure your DHCP server is authorized...if you haven't done it yet.. 1. Open DHCP in MMC. 2. In the console tree, click DHCP. 3. On the Action menu, click Manage authorized servers. The Manage Authorized Servers dialog box appears. 4. Click Authorize. 5. When prompted, type the name or IP address of the DHCP server to be authorized, and then click OK. ping here..if your problem still persists... cheers..

please ensure that you have dns properly configured in your dhcp server and if possible please post the unedited ipconfig /all from the doamin controller and from one of the cleint.Thanks Syedhttp://technetfaqs.wordpress.com