On Wed, 6 Aug 2014, Casey Deccio wrote:

      Why does google dns seems so inefficient at caching?

Google's implementation seems to recursively query for and cache ANY based on 
the entire set of records for the same name,
rather than on a per-record basis.  nohats.ca includes an NSEC3PARAM record 
with TTL 0.  This results in zero caching of ANY
queries.

I can confirm that changing the signed zone and setting the NSEC3PARAM
TTL to 86400 instantly reduced the stream of ANY queries from a few
hunderd qps to a few qps. (My apologies to whomever is the victim of
this attack - I guess google's cache will be more effectively DDoSing
you now via the open resolvers)

So I guess it's worth poking the recursive resolver people about.

Paul
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