[olug] DNS Cut Over -- TTL vs. Expires

[Jeff Hinrichs]

We're switching ISPs coming up and since we host our own DNS I probably
need to make some changes so everyone(other DNS servers) knows to
refresh their information in a more timely manner.

I am confused between Time To Live (TTL) and Expires. (that is what
happens when you only occasionally have to monkey with your DNS servers
;[) Do I need to decrease both of them or just one or the other?
Currently:

TTL = 38400 seconds
Expiry = 604800 seconds


Also, what would be a sane amount to turn them down ?  1Hour, 10minutes,
etc?


Thanks,

Jeff