Changing IP address block, help with dns

[Will Yardley]

In article <aui0b6$f076$1 at isrv4.isc.org>, Jan Pieter wrote:
> tom wrote:

>> Hi all, our current T1 provider is leaving the biz at the end of the
>> year.  We have a new T1 up and running as of yesterday.  I want to
>> switch our office network over to this new T1 next week.

>> There are 3 domains that will need to have there DNS changed to these
>> new IP addresses.  Fortunately, DNS is being hosted at another
>> facility on a different network.
>> 
>> What I am wondering is how to best update the DNS record files.  I
>> think what I want to do is lower the TTL value from 3 days to like 30
>> minutes (1800 sec), but do it now a few days before I intend to switch
>> the networks.

> If you have the 2 T1 lines at the same time, maybe you can connect
> your network to these 2 lines. Just point your DNS records to the
> new IP's, and after the TTL you disconnect the old line.

Also, if you can get both working at the same time, you can configure
both new and old IPs on your machines, and configure them to respond to
requests on  both IPs. However, simply reducing the TTL and doing the
switch should probably do the trick just fine.

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