TTL question

Barry Margolin barmar at alum.mit.edu
Sat Oct 1 01:11:26 UTC 2005


In article <dhk5hs$fab$1 at sf1.isc.org>,
 Kevin Darcy <kcd at daimlerchrysler.com> wrote:

> mahermick at gmail.com wrote:
> 
> >Hi Folks,
> >
> >I'm trying to understand the implications of not lowering the TTL for a
> >record prior to it being changed.
> >
> >Taking a hypothetical situation - I have an Primary MX record with TTL
> >of 3600 (1 hour) and no Secondarys (for arguements sake).
> >
> >If I changed the MX record would the maximum time my mail would be
> >unavailable be one hour or is it possible that it could take longer?
> >
> Correct, but you are *required* to have at least 2 nameservers for a 
> zone. So there's always going to some propagation time between them 
> unless you make the change on all of them simultaneously (in BIND terms, 
> that means they would all have to be configured as "type master").

If you use NOTIFY, the propagation time around a minute at most, 
effectively negligible compared to the 1-hour TTL.

-- 
Barry Margolin, barmar at alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***



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