dns1 named[1376]: client 125.162.42.67#64136: update 'swisscontact.or.id/IN' denied

I keep getting log messages like the following. Why?
Jun 21 12:00:00.000 client 10.0.0.1#1234: update denied
A:
Someone is trying to update your DNS data using the RFC2136 Dynamic Update protocol. 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 http://support.microsoft.com/support/kb/articles/q246/8/04.asp for information about how to turn them off.