I host a Magento website that I want to migrate to a new server without causing too much down time. The URL will stay the same but the DNS settings will be changing.
I'll be putting a upgrade notice on the current site to stop user interaction, zipping up the site and copying it from one server to another and when it's all set up I'll update the domain record to point to the new server.
My worries are about DNS propagation, etc. And specifically integration with 3rd party website such as PayPal, WorldPay, etc. My main concern is that once the site is moved someone who hasn't been to it before see's the new version on the new server. They put through an order which gets sent off to PayPal/Worldpay. Both these services use return/IPN url's to return the confirmation data back to the server. But if the DNS info hasn't propagated back to them they will be sending this data back to the old server.
I understand a way to limit downtime is to lower the TTL setting, wait until the current timeout, do the migration, then put the TTL back. But I read somewhere that not all DNS servers will accept a lower TTL?
Is there a better way to be moving this website?