Interaction of CNAME and A records with regard to TTL

Tim Maestas tmaestas at dnsconsultants.com
Thu Jan 23 02:50:11 UTC 2003


On Wed, 22 Jan 2003 Mark_Andrews at isc.org wrote:

> 
> > Hi,
> > 
> > thank your for your answers. A follow-up question: how about the TTL of
> > CNAME records and the records they point to, is there a constraint that they
> > have to be equal? (I assume that not.)
> 
> 	Correct.

	One note that may be worth mentioning - the Microsoft Windows 2000 
	caching resolver will cache both the CNAME and the A record that
	it points to at the same TTL.  If the TTL's are different then
	it will cache at the lower of the two (thereby putting them
	within the *letter* of the RFC, but, IMHO, not the spirit.

-Tim




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