[H-GEN] DNS Question for the DNS Gurus

[Greg Black]

On 2006-11-16, Rick Phillips wrote:

> does anyone know if I can have my
> backup DNS server (on another machine and on another ISP) be changed to
> point to my new address while my own DNS server points to my current
> address.

> The theory is that when the changeover happens, the new IP address will
> be available to the world immediately off the backup server.  My own DNS
> server can be changed after the event to match.  Would this work?

You can't sensibly have different name servers advertising
different data.

There is no "immediately" in the DNS.

At the least, you need to shorten the TTLs in all your records
so that correctly functioning hosts will know not to cache your
data for too long (and you have to know that there's nothing at
all you can do about the large number of incorrectly operating
hosts out there).

For something like this, I'd reduce all TTLs to about 30 minutes
right now and I'd leave them like that until after the change
happens.  When you get your new connection and you know for sure
what your new IP address is, then you can update the various
name servers.

Greg