We are going to be moving from one ISP to another in the next month or so, and I will be changing the TTL's down to 60 seconds on the DNS servers that I have authority for, but our current ISP has authority for the reverse DNS zone.
Since this is the first time I have ever been through something like this, I'm wondering what to expect, and when I should do things (most likely the weekend, when email traffic is slow)
I know how to do all the changes on my side as far as DNS goes, both at our registrar, and our authoritative DNS server, as well as making sure our secondary DNS servers get the latest zone transfers. However, since the IP addresses of our current netblock is from our ISP, I am wondering what the best approach for this would be. I'm thinking something along the lines of this:
1) Request that the TTL's for our current IP's be reduced to 60 seconds.
2) Give all the information to our NEW ISP for what IP's will have for the hostnames, and tell them to hold tight.
3) On the day of the 'move', tell our old ISP to change the hostnames from what they are now, back to their 'default' hostnames. And then, tell our new ISP to make the new hostnames 'live' as far as the PTR records go.
Never having done this before, I'm just wondering what other people do, to make this as seamless as possible. I'm confident in my ability to reduce the TTL's of our current DNS records, and on the day of the move, to change the IP's to the new ones for our hostnames, but I don't have any control over the PTR records, and will be relying on 2 different ISP's to make changes.
What do other folks do in these situations?