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Re: [PLUG] OT: spammer's DNS
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On Wed, Apr 01, 2009 at 03:02:02PM +0200, sean finney wrote:
> maybe they have a poor implementation of DNS caching, or maybe it's
> intentionally designed that way.
In at least some cases it's likely intentional. One technique for
identifying bots is to search for end-user systems which are performing
a disproportionate number of MX lookups. By not using DNS, bots can
circumvent this technique.
-mct
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