DDNS Record Refresh Period

Hi

I am reading different even conflicting information regarding the refresh periods of DDNS records for machines with statically assigned addresses, so can anyone clarify whats what.

It appears that pre Windows 2003 SP1 the refresh period is 1 day or 60 minutes for DCs

But then later articles say the refresh period is 7 days. So whats right. Does it change by OS.

Part two of the question if it is 7 days how does that work if Scavenging is set 7 days no-refresh and 7 days refresh. What ensures timestamp is refreshed before it is scavenged.

Any pointers would be appreciated.

Thanks