transfer issue

[ljwhite]

I am trying to transfer all the data from old server to the new one. But I’m concerned about how real time the switchover will be done. We need to make sure that all data files (ie. emails) are switched over real time so that a minimal number of emails will be lost.
Any suggestion about this?

[Stefaans]

I suggest you set the TTL values of the relevant DNS zones to a short value a day ahead of the transfer, e.g. 600 (10 minutes). In theory this means that no ISP should cache your old DNS zones for very long, and hence start using the new server shortly after the transfer. Yes, this is not real-time, but if you can do this after hours, it gets pretty close :-)

If using WHM's transfer functions, each DNS zones will be updated to the default value (as per your DNS templates) again. However, I have found that the updated DNS zones don't always load automatically after transfer, in which case I would do a "rndc reload" from the shell.

[ljwhite]

Thanks for your suggestions. How could I lower the dns TTLs for our domains?