At 15:10 26 02 97 -0600, you wrote:
You're making lots of assumptions.
1) That client DNS systems will actually honor such a TTL. Many don't (claim they're broken all you want, but these are the facts).
2) That client SOFTWARE will actually go back and ask again for the IP number. Several won't (Netscrape being rumored to be one of them). TTLs are irrelavent in that case.
Go ahead and try to tell your customer, who purchased web service from you, that you have the right to disrupt their operations at any time and under any pretense and see how many of them you have left.
I would hope that your contract didn't state the customer was guaranteed the same IP for eternity; if so, your legal department needs to be hanged. You can either renumber once into an RFC 1918 block and use NAT, or you can renumber into a new space every time you change providers. Your customers will understand renumbering once, especially if you can find a way to improve services with it. They'll look elsewhere if it happens more than once or twice, or if they get nothing from it.
Tell you what. You get ALL the providers to agree via BCP that all customers must run NAT on their leased line connections. Every one of them. That is, a nice level playing field. Then come back here and let's talk. Or is this a "big guys don't have to" thing again? Because if it is, then you're right back where you started. -- -- Karl Denninger (karl@MCS.Net)| MCSNet - The Finest Internet Connectivity http://www.mcs.net/~karl | T1's from $600 monthly to FULL DS-3 Service | 99 Analog numbers, 77 ISDN, Web servers $75/mo Voice: [+1 312 803-MCS1 x219]| Email to "info@mcs.net" WWW: http://www.mcs.net/ Fax: [+1 312 803-4929] | 2 FULL DS-3 Internet links; 400Mbps B/W Internal