Jerod M. Bennett wrote:
> Classic DNS FAQ.
>
> 1) Check current DNS time to live
> 2) change DNS time to live to 5 minutes
> 3) wait for old DNS time to live
> 4) shutdown old IMail server
> 5) change DNS info to new IMail server
> 5b) Optional - Wait 5 minutes
> 6) startup new IMail server
> 7) change DNS time to live back to original value

A few minor tweaks:

#3 should be old DNS TTL plus refresh value unless you're sure your
master is NOTIFYing the slaves and that they respond to it.  You want
to protect against the case where a slave responds with the old TTL
just before it fetches the new lower value.

#5b isn't needed, in fact is detrimental.  If a host gets the new MX
record from the master before you start the new server the email will
be delayed.  I'd delete #5b and move #6 anywhere before #5.

#7 should be folded into #5, there's no reason to hand out short TTLs
for the new info.

> Usually you will find your current time to live to be about 7 days.  So
> you won't be able to change servers for that amount of time.

IMHO 7 days is reasonable for a SOA expire value but its a bit high
for a TTL unless you've got a really stable environment.

--
[EMAIL PROTECTED]     "The avalanche has already started, it is too
Rod Dorman              late for the pebbles to vote." � Ambassador Kosh


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