// rfc 2317 allows arbitrary cidrs to be delegated. so far, // i've always been able to get reverse mappings set up // for static addresses.
I think you've been lucky, or have been dealing with better ISPs. Apart from my home ADSL line, I share a commercial SDSL with some folks. We've got a /123 or /124 (I forget right now) which they won't delegate. Which seems reasonable, from a network management point of view, I guess. When we asked, they gave us an email address to mail updates to; the human on the other end was always responsive and the updates got in place quickly. Then one day the email address stopped working, and further inquiries returned the same email address (including in mail where we're complaining that it didn't work). Reality has slowly diverged from our published reverse mappings. Thankfully (?), I've seldom found this to be a problem for mail, in practical terms. I use one of these mismatched hosts as my mail server (after my ISP's went flaky again), and get less than a dozen rejects a year (although it's an admitedly low-traffic site). Anthony
