[dns-operations] NXDOMAIN responses from DE nameservers

Peter Koch pk at DENIC.DE
Wed May 12 18:29:40 UTC 2010

Dear colleagues,

as already discussed on some operational mailing lists, the DE nameservice
faced an incident earlier today (2010-05-12). Starting around 11:30 UTC and
lasting until 13:45 UTC several of the authoritative nameservers for the DE
top level domain returned NXDOMAIN responses for a yet to be determined number
of DE domains that existed in our registration database.  At that later point
in time, all affected servers had either been disabled or fed with an earlier
version of the DE zone.
Regular operations were eventually resumed at 15:00 UTC.

The negative caching TTL for DE is set to 7200, leading to a latest
presence of such NXDOMAIN responses at 15:45 UTC, provided regular
handling of both NXDOMAIN and negative TTLs was in use at caching resolvers.

The issue has been dealt with by an internal incident response team.
DENIC will provide further details after a root cause analysis.

Please refer to <http://www.denic.de/en/denic-in-dialogue/news/> for
future announcements during the upcoming days. {News might be provided
in English with some delay.}

Kind regards,
   Peter Koch, DENIC eG

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