I keep getting log messages like the following. Why? Jun 21 12:00:00.000 client 10.0.0.1#1234: update denied

Someone may be trying to update your DNS zone using the RFC 2136 Dynamic Update protocol, but they may not have permission to do so.

Windows 2000 machines have a habit of sending dynamic update requests to DNS servers without being specifically configured to do so. If the update requests are coming from a Windows 2000 machine, see https://support.microsoft.com/en-us/help/246804/how-to-enable-or-disable-dns-updates-in-windows-2000-and-in-windows-se for information about how to turn them off.

If you get this log message when trying to perform a DNS update with a program such as nsupdate, please check your named configuration.