When your DNS service starts, it reads the cache file, which you probably keep current by downloading from the InterNIC.
If the AutoCacheUpdate value does not exist in the registry, or has a non-zero data value, the DNS server will rewrite the cache file, which may contain bogus entries.
To turn off this feature, browse to
Add Value name AutoCacheUpdate as a type REG_DWORD and set it to 0.
Note: SP4 considers AutoCacheUpdate to be zero if the value name is missing.
With the DNS Service stopped, copy the Cache.dns file from the backup folder
(%SystemRoot%\System32\Dns\Backup) to %SystemRoot%\System32\Dns.
Start the DNS Service.