DHCP clients may take a long time to register their names on a DNS server that is running Windows Server 2003

Dynamic Host Configuration Protocol (DHCP) clients may take a long time to register their names on a Domain Name System (DNS) server that is running Microsoft Windows Server 2003. DHCP client names cannot be resolved until their names are successfully registered on a DNS server. Applications that rely on name solution may stop working because of name resolution failure.

This problem occurs if the following conditions are true:

�	A centralized DNS server is configured on a Wide Area Network (WAN). This DNS server owns all DNS zones.
�	Some local cached DNS servers are configured on the local area network (LAN).
�	One or more local DNS servers are configured for every DHCP scope.
�	Many DHCP renewal requests occur because the DHCP clients roam aggressively.

For every DHCP renewal request, the DHCP server puts the name registration request of the DHCP client in a queue. Then, the DHCP server handles the requests one by one. When the DHCP server handles the DHCP client request, the DHCP server has to contact both a local DNS server and the centralized DNS server. This is because the local DNS server does not own DNS zones for every request. Therefore, unnecessary network traffic occurs over the WAN. This traffic delays the resolution of DHCP client requests. If the volume of the DHCP requests is large, it takes a long time for some DHCP clients to register their names.

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, submit a request to Microsoft Online Customer Services to obtain the hotfix. To submit an online request to obtain the hotfix, visit the following Microsoft Web site: Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. To create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" section and the online request forms display the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Prerequisites

Microsoft Windows Server 2003 Service Pack 1 (SP1) and the DHCP component must be installed on the computer.

Restart requirement

You have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

Windows Server 2003 with SP1, x86-based versions

File name	File version	File size	Date	Time	Platform
Dhcpssvc.dll	5.2.3790.2935	271,872	11-May-2007	17:29	x86

Windows Server 2003, x64-based versions

File name	File version	File size	Date	Time	Platform	SP requirement	Service branch
Dhcpssvc.dll	5.2.3790.2935	434,176	11-May-2007	03:32	x64	SP1	Not Applicable
Wdhcpssvc.dll	5.2.3790.2935	271,872	11-May-2007	03:32	x86	SP1	WOW

Windows Server 2003 with SP1, Itanium-based versions

File name	File version	File size	Date	Time	Platform	SP requirement	Service branch
Dhcpssvc.dll	5.2.3790.2935	735,232	11-May-2007	03:32	IA-64	SP1	Not Applicable
Wdhcpssvc.dll	5.2.3790.2935	271,872	11-May-2007	03:32	x86	SP1	WOW

Post-installation instructions

Important This article contains information about how to modify the registry. Make sure that you back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base:
After you install this hotfix, you must create the AlternateDnsServer registry key. After you do this, the DHCP server will directly send name registration requests to the correct DNS servers. Network traffic over the WAN decreases. Therefore, the performance of the DHCP server improves.

To create the AlternateDnsServer registry key, follow these steps:

1.	Click Start, click Run, type regedit, and then click OK.
2.	Locate and then double-click the following registry subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Dhcp\Parameters
3.	On the Edit menu, point to New, and then click Key.
4.	Type AlternateDnsServer, and then press ENTER.
5.	Right-click AlternateDnsServer, click New, and then click String Value.
6.	Type the IP address of the other DNS server as the name of the registry entry, and then press ENTER. Note Under the new AlternateDnsServer registry key, you may repeat step 6 to create several registry entries if you have several DNS servers.
7.	On the File menu, click Exit to close Registry Editor.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.