Oh no. You go to log on to your favorite website, and can't reach it. You remember something in the motd about a new IP address, and maybe using IRC to find out the new one, but isn't this what that whole DNS thing was supposed to fix?


However, most people don't use DNS properly. Odds are, they have a global TTL of 86400 seconds in their zone file, which means that when you do a dig against their authoritative nameserver, you'll get something like:

www.everything2.com.    1D IN A
This means they are giving out an A record, with a 1 day ttl. But, when you query your local recursive nameserver, you get:
www.everything2.com.    3h49m28s IN A

This means that about 20 hours ago, someone asked your nameserver for this info, and it went forward to the authoritative nameserver. The local nameserver will cache the response for a full day - that's what it was told to do - and continue to give out a bad answer. oops.

The right thing to have done was, about 2 days before the IP change, drop the TTL to 2 hours. Then, about 4 hours before the switch, drop it to 5 minutes. Then, when you make the switch, there is, at most, a 5 minute user outage.

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