DNS ROOT understanding

Jonathan de Boyne Pollard J.deBoynePollard at Tesco.NET
Fri Nov 12 04:43:53 UTC 2004

JR> [...] if your name server is well-behaved, it will only communicate
JR> with a root server 4 or 5 times a week: every time it queries for a
JR> domain name in a TLD that hasn't been cached already.

Wrong.  It will also communicate with a root server once each for _every
individual_ domain name looked up that isn't under one of its delegated
TLDs (which will include a wide range of things from the ever-popular
"localhost.localdomain." to single-label "AAAA" lookups generated by the
broken search path mechanism in IPv6-aware GLIBC), and will cache the
resultant negative responses for at most 24 hours (and so, given its
popularity, will probably ask a root server about
"localhost.localdomain." at least once per day).

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