Replacing root hints with the Cache.dns file

You may experience one or more of the following symptoms:

• The DNS server is unable to resolve names for which it is not authoritative.
• There are no servers listed on the DNS server Root Hints tab.
• The servers listed on the Root Hints tab do not match the Cache.dns file in the %systemroot%\system32\dns folder.
• When you replace the Cache.dns file in the %systemroot%\system32\dns folder, it does not update the root hints listed in the DNS Manager.
• The following events are logged in the system event log:

  Event ID: 453
  Description: DNS Server sendto () function failed. The data is in the error.

  Event ID: 7053
  Description: DNS_EVENT_SENDTO_CALL_FAILED
  DNS Server sendto () function failed. The data is in the error.

This issue can occur if either of the following conditions is true:

• The Cache.dns file is missing or corrupted.
• The DNS server is a domain controller and is configured to load zone data on startup from Active Directory and from the registry.

If the root hints specified in Active Directory have been deleted, modified, incorrectly entered, or damaged, this behavior occurs.

To work around this issue if the DNS server needs hints for the Internet root servers:

1. If it is running, quit the DNS MMC snap-in. At a command prompt, type net stop dns, and then press ENTER.
2. After the DNS Server Service stops, type copy %systemroot%\system32\dns\samples\cache.dns %systemroot%\system32\dns, and then press ENTER. Note that if you are prompted to overwrite an existing file, type y, and then press ENTER..
3. Start the Active Directory Users and Computers MMC snap-in. Click Advanced Features on the View menu.
4. Expand the System folder, expand MicrosoftDNS, right-click RootDNSServers, and then click Delete.
5. Click Yes when you are prompted to delete this object, and then click Yes again when you are prompted to delete this object and the objects it contains.
6. Quit the Active Directory Users and Computers MMC snap-in.
7. At the command prompt, type net start dns, and then press ENTER. Exit the command prompt.
8. Start the DNS MMC snap-in, and then verify that the root servers appear on the Root Hints tab in the server properties.
9. Start the Active Directory Users and Computers MMC snap-in, and then verify that the RootDNSServers container has been recreated and contains the root servers that were listed in the DNS Manager. If multiple domain controllers exist that are running DNS, the new root hints are automatically be replicated.

By default, when DNS is running on a Windows 2000 domain controller, the root hints are read from Active Directory upon startup first. If no root hints exist in Active Directory, the Cache.dns file is read. If the listing of root DNS servers becomes damaged in Active Directory or is missing, it may be necessary to replace them with the entries listed in the %systemroot%\system32\dns\backup\Cache.dns file.

The following methods are available to determine how the DNS service initializes and provides service when started:

From the registry

This initializes the DNS Server service by reading parameters stored in the Windows registry.

From a file

This initializes the DNS Server service by using an optional boot file, as used by Berkeley Internet Name Domain (BIND) servers. To use this file, provide a copy of a boot file from another DNS server that is running a DNS server based on the BIND implementation. On BIND-based DNS servers, this file is typically the Named.boot file. The format of this file must be the older BIND 4 format, not the more recent BIND 8 boot file format. If used, settings and directives in this file are used instead of comparable settings stored in the registry on the DNS server computer. For any parameters not configurable using boot file directives, registry defaults (or stored reconfigured server settings) are applied by the DNS Server service.

From Active Directory and registry

This initializes the DNS Server service by reading parameters stored in the Active Directory database and the server registry. For Windows 2000 DNS servers, this is the default boot option.