[Tfug] Recommended DNS TTL values

[Jeffrey Clark]

mine is set to 604800 (7 days).  i rarely modify my dns settings so that
works out fine for me.  if you are really that anxious to get to your newly
hosted email server you can always add a hosts entry on your local machine.

jeff

On Wed, Oct 15, 2008 at 4:42 PM, Matt Jacob <matt at devgenix.com> wrote:

> Hello friends,
>
> Before anyone makes an accusation that this topic is OT, please sit down
> and be quiet for a moment. Consider the fact that BIND is still the most
> popular DNS server currently in use and that BIND runs on Unixes. DNS,
> therefore, is inherently a Unix-like topic. And since we all use DNS every
> day on a variety of Unixes, whatever I just said in the previous four lines
> has already become moot. Anyway, onto more pressing issues...
>
> What are "reasonable" numbers for DNS TTL values? It seems like I usually
> set up DNS and forget about it until I need to change something or until
> something breaks. Lo and behold, I'm moving to a new mail server soon, and
> the issue has come up again (mostly because I want a clean transition, but
> also because it makes for a fun educational argument).
>
> So, I've got some thoughts. Currently, my TTL is 86400 for all record types
> across all my domains. For the purpose of switching to a new host, I usually
> lower my TTL to 300 for the cutover and then bring it back up again once
> everything is working. The problem is that 24 hours is a long time to wait
> before changes become active (i.e., I want to use my new mail server NOW!).
> I'm considering changing my standard TTL to 10800, which seems fairly common
> and is much more reasonable for making changes. Why wait 24 hours when you
> only have to wait 3 hours, right?
>
> Is that too low of a value for day-to-day use? In some cases, it probably
> doesn't even matter, e.g., when dealing with DNS servers that don't honor
> TTL values and hold onto records for way longer than they should (a la
> Comcast and other cable providers). Burning up DNS query bandwidth isn't
> really an issue for me since I use third-party DNS servers through my
> hosting provider.
>
> What's a happy medium? Is 10800 good, or will I burden the internet with my
> ultra-popular sites? (100 uniques a day is considered high-traffic,
> right...?) :-P What does everyone else do?
>
> Matt
>
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