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[DENICpublic-l] Background of the Partial Failure of the Name Service for .de Domains

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  • From: DENICpresse <presse AT>
  • To: Public-L <public-l AT>
  • Subject: [DENICpublic-l] Background of the Partial Failure of the Name Service for .de Domains
  • Date: Fri, 14 May 2010 18:39:53 +0200
  • List-id: public-l <>

Dear Sir or Madam,

As promised, following you will find detailled information about the
disturbance of the .de domain nameservice which occured last Wednesday.
Answers to the most frequently asked questions have been collected for you
in the attached FAQ-document.

Course of Events and Effects
Starting about 13:30 (CEST) on Wednesday, 12 May 2010, DENIC faced the
situation that, depending on the service location and the domain queried,
users sometimes received the incorrect reply “domain does not exist”. In
such cases, the respective user could not reach the .de domain concerned
via the domain’s address, and e-mails from or to this address were
rejected or not sent.
The reason why this situation occurred was an incomplete copying process
during the regular name service data update, which is performed at 2-hour
intervals. Due to this, an incomplete update of the name service data (a
so-called zone file) was triggered at 12 of the 16 service locations.

The immediately activated incident response team analyzed the error and
subsequently, starting at 14:20, successively switched off those locations
that were giving faulty responses.
Since it was not immediately clear whether the reason for the zone defect
was a faulty database or a fault in the zone generation process, the
registration systems were also temporarily put on hold. The latter was
also decided due to the fact that the registration systems had to cope
with a high load stemming from an unusually high number of registration
attempts of reputedly available domains.

Starting at 14:30, the switched-off locations were successively provided
with a complete zone file and re-integrated into the name server network.
Due to the data volume and the worldwide distribution of the locations,
the entire distribution process and the subsequent re-start of all the
service locations concerned took until about 15:45. At this point in time,
with respect to DENIC, the service had been fully restored with its full

However, due to the caching of ISPs, Internet users might sometimes have
had to put up with disturbances up to 2 hours after the resolution by

After completion of the ongoing detailed analyses, additional actions
might have to be considered.

Technical Details
The zone file generated from the registration database is checked for
completeness and plausibility several times before it is released for use
by the globally distributed locations. These checks were also successfully
executed for the named zone file. This is the reason that four locations
were not provided with a faulty zone file and that the Frankfurt IPv6 DNS
location and the DNSSEC testbed were not affected.

However, within the scope of a project for creating a new name service
infrastructure, the concept for the zone file distribution was also
redefined. All the quality checks mentioned above were positively applied
to the named zone file as well, but, according to the new concept the zone
was copied once again, before it was distributed to the locations. This
copying process was interrupted resulting in a file that held just one
third of the domain data.
Provisions were even in place to insure the copying was performed
correctly. Unfortunately, since the securing mechanism itself wasn’t
working properly the copying error was not detected and processing was not

As such, the incident is not related to the switch of the data centre
operation from Amsterdam to Frankfurt, which took place on the preceding
Tuesday. Neither is there any correlation to the DNSSEC testbed, nor were
services provided for cooperating partners or secondaries operated by
DENIC for other TLDs affected. The incident would not have had any impact
on the anycast services we are planning to provide for our TLD customers

Kind regards

Beate Schulz
Business Services - Public Relations


Kaiserstraße 75-77
60329 Frankfurt am Main

E-Mail: presse AT
Fon: +49 69 27235-274
Fax: +49 69 27235-235

Angaben nach § 25a Absatz 1 GenG:
DENIC Domain Verwaltungs- und Betriebsgesellschaft eG (Sitz: Frankfurt am
Vorstand: Sabine Dolderer, Helga Krüger, Carsten Schiefner, Dr. Jörg
Vorsitzender des Aufsichtsrats: Elmar Knipp
Eingetragen unter Nr. 770 im Genossenschaftsregister, Amtsgericht
Frankfurt am Main

Attachment: FAQ_Nameserver_disturbance_P.pdf
Description: Adobe PDF document

  • [DENICpublic-l] Background of the Partial Failure of the Name Service for .de Domains, DENICpresse, 05/14/2010

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