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From Andrzej Adam Filip <>
Subject Re: DUL/DUL+ redesign to improve DNS cache hit ratio [SA v. MTA]
Date Wed, 06 Jul 2011 18:13:43 GMT
"David F. Skoll" <> wrote:
> On Wed, 06 Jul 2011 08:15:47 +0200
> Andrzej Adam Filip <> wrote:
>> It may improve performance e.g. in case of hundredths mail servers in
>> a data/co-location center using shared forwarder and rejecting on
>> first DNSBL hit. Somehow I doubt buying data for such "reseller"
>> configuration is legally encouraged  by paid DNSBL operators.
> This is true.  But it's also not in paid DNSBL operators interest to
> improve the hit ratio.  If the cache hit ratio is improved too much,
> the DNSBL operators would be unable to detect heavy users and ask
> (threaten) them for money. :)  In the limiting case, if the cache
> becomes *too* effective, the organization hosting the cache *is*
> effectively providing the whole data set to its users.

To put it short:
a) Only DNSBL listing "net ranges" (e.g. DUL/DUL+, network "reputation")
   can be quite easily redesigned to improve DNS hit ratio (IMHO)
b) Free of charge DNSBL would benefit the most
c) In case of DUL list quality is not (IMHO) defined by big */16 entries
   (e.g. home ADSL ranges) that will generate most DNS cache hits

[pl>en: Andrew] Andrzej Adam Filip :
I do not believe that this generation of Americans is willing to resign
itself to going to bed each night by the light of a Communist moon...
  -- Lyndon B. Johnson

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