[lug] DNS Time

[Jeffrey B. Siegal]

"Shannon M. Johnston" wrote:
> What gives?

Two things:

1. The TTL value in the records themselves.  

2. The refresh time for the secondary name servers (not an issue with newer
name server code, because it will probe the secondaries to get them to reload
when you update the primary).

The default for both of these is set in the SOA record.  

The key to moving something and not having to way for the changes to propogate
is to reduce the TTL and refresh time *before* the move down to something very
low, like five minutes.  Then wait for the old data to age out (which could
take a day or two).  Then move the stuff, update the DNS, and increase the TTL
and refresh back up to a reasonable level (24 hours+).  Since the data being
cached when you do the move has five minute timeouts, everything should be
updated within five minutes, worldwide.