[mdlug] Server maintenance

[Michael Mol]

On Nov 17, 2012 6:41 AM, "Jay Nugent" <jjn at nuge.com> wrote:
>
> Greets,
>
>
> On Fri, 16 Nov 2012, Carl T. Miller wrote:
>
>> s/propagating/promulgating/
>>
>> ; -)
>>
>> c
>>
>>
>> On 11/16/2012 05:38 PM, Mat Enders wrote:
>>>
>>>  Hello all I will be taking down the MDLUG web and email server within
the
>>>  next ten minutes.  I hope to have it back up with 2-3 hours.  This
going
>>>  to
>>>  involve a change to DNS so part of it will be that propagating.
>
>
>    DNS *NEVER* propogates.  You plan ahead, reduce the TTL/Expire to just
a couple hours.  Once that *old* TTL has passed, begin your maintenance.
Sheesh!  I teach this basic stuff every day yet see this mistake over and
over and over...

That works in theory, but it rather sucks when caching resolvers override
(or simply ignore!) TTL.

Best-effort "safe" assumption is 24 hrs, regardless of how low you set your
TTLs.