Newbie question: determining best values for use in $TTL and SOA on Bind 8.2.x

[Barry Margolin]

In article <37C68301.684EECD8 at cyber-wizard.com>,
Albert T. Croft <acroft at cyber-wizard.com> wrote:
>My question is how can I determine the "best" values to use
>for the $TTL line and SOA record for the domains I work
>with, or are there such a set of values that are already
>highly recommended? I read through the section in the
>Cricket book where the RFC recommended values for a root
>server were given, and have values similar to the ones in
>the Cricket book currently, but was wondering if there is a
>way to determine the "best" such values.

There's no "best" value, it depends on your needs.  Lower TTLs mean that
changes will propagate faster, but at the cost of more load on your
authoritative servers because cached data will have to be refreshed more
often.

If you can anticipate changes, the recommended practice is to keep your
TTLs high most of the time, and then lower them in advance of the changes.
We use 1 day as our normal TTL.  The day before an important change we
lower the TTL to something like 15 minutes, so that when the change is made
the stale data will be discarded quickly.

-- 
Barry Margolin, barmar at bbnplanet.com
GTE Internetworking, Powered by BBN, Burlington, MA
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