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  2. DNS: Admin: "Use root hints if no forwarders are available" results in the opposite behavior if toggled in W2K8 DNS snap-in

DNS: Admin: "Use root hints if no forwarders are available" results in the opposite behavior if toggled in W2K8 DNS snap-in

Symptoms

  1. Install a Windows Server 2008 SP1 or SP2 DNS Server.

  2. From the Start menu, click "All Programs" -> Administrative Tools -> DNS.

  3. In the DNS Manager snap-in (Dnsmgmt.msc), right-click the node containing the name of the DNS server.

    DNS
       [-] <DNS Server Name>               <- Right Click Here
          [+] Global Logs
          [+] Forward Lookup Zones
          [+] Reverse Lookup Zones

  4. In the forwarders tab, toggle the setting for "Use root hints if no forwarders are available."

    Enabling the checkbox for  "use root hints if no forwarders are available"  in the Windows Server 2008 DNS Manager snap-in, DNSMGMT.MSC, actually disables the use of root hints.

    Unchecking the checkbox for “use root hints if no forwarders are available” in the Windows Server 2008 DNS Manager snap-in, DNSMGMT.MSC, actually enables the use of root hints.

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Cause

A code defect in the Windows Server 2008 SP1 (RTM) and Service Pack 2 version of Dnsmgmt.msc causes the DNS service to use the opposite behavior than the Use root hints if no forwarders are available checkbox in the DNS Manager snap-in.

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Resolution

This problem does not exist in the Windows Server 2008 R2 version of Dnsmgmt.msc.

As a workaround, you can use the Windows Server 2008 version of the DNSCMD tool, which correctly displays and configures the root hint behavior. Otherwise use the opposite checkbox configuration to obtain the desired behavior. See the "More Information" section for the DNSCMD tool syntax.

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More Information

The Use root hints if no forwarders are available checkbox in Windows Server 2008 DNS Manager is equivalent to the Do not use recursion for this domain in the Forwarders tab of the Windows Server 2003 DNS Manager snap-in.

Toggling the use root hints if no forwarders are available checkbox (or its Windows Server 2003 equivalent) modifies the following registry value:

Value Name: IsSlave
Value Path: HKLM\SYSTEM\CurrentControlSet\Services\DNS\Parameters
Value Type: REG_DWORD
Value Data: 0 | 1 (Default value: 0)

Value

Meaning

0

Not a slave. If the forwarder servers do not respond, the DNS server issues standard iterative queries to try to resolve the remote name.

1

Is a slave. If the forwarder servers do not respond, the DNS server terminates the search and sends a SERVER_FAILURE response to the query.

The DNS Server service and DNS Manager snap-in both read DNS registry entries only on startup. You can change entries while the DNS server is running by using the DNS console or DNSCMD tool. If you change entries by editing the registry or by using the DNSCMD tool, the changes are not effective until you restart the DNS Server service. Similarly, if DNS server registry keys are modified directly, restart the DNS Manager snap-in, Dnsmgmt.msc, so that it will reflect current configuration settings.

To view the status of the IsSlave setting in the registry using DNSCMD.EXE use the command:

c:\>dnscmd /info

To modify the value of the IsSlave setting using DNSCMD.EXE:

c:\>dnscmd /config /isslave 0

OR

c:\>dnscmd /config /isslave 1

Sample output from "dnscmd /info" is shown below:

Query result:
Server info
 server name           = dc1.contoso.com
 version                  = <build #>
<truncated for brevity - scroll to bottom of DNSCMD output>
 forward timeout  = 5
 slave            = 0                             <----Current value in registry for IsSlave
Command completed successfully.

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Keywords: vkball, kb

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Article Info
Article ID : 2001154
Revision : 1
Created on : 1/8/2017
Published on : 1/15/2013
Exists online : False
Views : 136