Delays in Name Resolution Using Microsoft DNS Server Forwarder Option (251384)

SYMPTOMS

Clients that are using a Microsoft Domain Name Server (DNS) may experience a delay in name resolution if the Microsoft DNS server is using the "Forwarders" option and is set to use the "Operate As Slave Server" feature. This delay may be as long as 15 seconds.

CAUSE

This issue can occur under the following circumstances:

The client sends a single label unqualified name query to the DNS server.
The Microsoft DNS server sends a recursive query to its Forwarder to resolve the name.
The Forwarder returns a "Server Failure" or "Operation Refused" error message.

MORE INFORMATION

In Windows NT 4.0 Service Pack 4 and later, clients no longer send unqualified name queries to DNS by default. For additional information about related topics, click the article number below to view the article in the Microsoft Knowledge Base:

230744 Windows NT 4.0 SP4 DNR Does Not Send Unqualified DNS Queries

The following registry entry was introduced that helps control the behavoir of DNS Server: RecurseSingleLabel

Start Registry Editor (Regedt32.exe).
Locate the following key in the registry: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\DNS\Parameters
On the Edit menu, click Add Value, and then add the following registry value:
```
Value Name: RecurseSingleLabel
   Data Type: REG_DWORD
   Value: 0 (Default)
						
```
When set to 0, DNS will not recurse Single Label Queries except NS and SOA RR types.

Setting RecurseSingleLabel to 1 will recurse all RR types, but there will not be a 15 second delay before the answer is returned.
Quit Registry Editor.