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 performance.
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 DENIC.
After completion of the ongoing detailed analyses, additional actions might have to be considered.
For more details check out www.denic.de
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