NANOG list reverse DNS handling

[Iljitsch van Beijnum <iljitsch () muada com>]

A couple of days ago I moved my mail server, and inadvertently mistyped 
its name in the reverse DNS. After this, I noticed a message wasn't 
making it to the list. Investigation showed:

rcpt to: nanog () nanog org
450 Client host rejected: cannot find your hostname [83.149.65.1] info 
at: http://www.merit.edu/cgi-bin/mn/reversednsinfo

Ok, so far so good. But when I visited the URL mentioned in the 
rejection message, I just got a web form saying "Please enter your 
e-mail address and select your organization from the list below". 
Obviously this is meant to do _something_, but it's entirely unclear 
what and why.

After this the page I think should have been referred in the first 
place comes up: http://www.merit.edu/mn/support/reversedns.html

There is also a link to a DNS checking tool. However, this tool is 
pretty much useless in situations such as the one in which I found 
myself, as it doesn't answer the real question: what is the TTL for the 
offending DNS information.