Arrogant RBL list maintainers

Matthew Petach mpetach at netflight.com
Wed Dec 16 11:21:42 CST 2009


On Wed, Dec 16, 2009 at 5:21 AM,  <Valdis.Kletnieks at vt.edu> wrote:
> On Wed, 16 Dec 2009 07:06:55 EST, Mike Lieman said:
>
>> What's the word for 'mail server' in Lower Sorbian, and does your algorithm
>> properly detect it in a hostname?  See the problem here?
>
> When the hostname at that IP address is exactly one incremented character
> different than the preceding address, and one decremented character different
> than the following address, and that pattern holds across a /24, they're
> probably not mail servers.  Nobody has 256 'frzzmabs-1'..'frzzzmabs-256'
> servers in the same /24  for *anything* user-facing.
>

You clearly haven't set up webmail farms to handle half a billion accounts
before.  ^_^;

We name our (many thousands of) webmail front end boxes as
webXYYZZ.mail.$site.yahoo.com, so for cluster 3, farm 57, you
end up with a string of hosts all in a row like
web35701.mail.mud.yahoo.com
web35702.mail.mud.yahoo.com
web35703.mail.mud.yahoo.com
web35704.mail.mud.yahoo.com
web35705.mail.mud.yahoo.com
web35706.mail.mud.yahoo.com
web35707.mail.mud.yahoo.com
web35708.mail.mud.yahoo.com
...etc...
Take a look at the reverse DNS for the entire 66.163.178.0/23 subnet;
you'll find that when you're doing things at large scale, you can't really
get away from having sequentially numbered reverse DNS entries all
in a row, exactly as you seem to think "Nobody has".  :/

Matt




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