Re: [9fans] /n/sources/patch/spamhaus

[a@9srv.net]

// 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