All FAQ

No, there were no domain deletions. All domains remained unchanged in DENIC’s registration database.  A so-called zone file with technical information (DNS data) is created at regular intervals from this database, and is distributed by the nameservers.  It was only the distribution to some nameservers that caused problems.

The affected version of the .de-zone 2010051253 (created at 1:09 pm CEST) included the DNS data for all .de-domains (13672644).
Following the zone data update of the nameservers however, certain servers delivered correct data for 3837256 of the domains.  For all other domains non-existence was mistakenly asserted (so-called NXDOMAIN-Answer).

No. Since the DENIC domain database was not affected, DENIC’s other information services (whois, domain query, and domaincheck) delivered correct answers throughout.

 DENIC is a cooperative and its full name is “DENIC Domain Verwaltungs- und Betriebsgesellschaft eG”. It is the registry for the domains below the Top Level Domain .de, i.e. it administers all domains that end in .de. Additionally, DENIC is the registry for all ENUM-domains which cover the German telephone number space.

The domain administration is an operation requiring the most sophisticated technology. Its most essential components are the provision of an automatic electronic registration system and the operation of the domain database and the name-server service for the .de zone and the German ENUM zone. DENIC's database thus contains information about which domains have already been registered, who the domain holder is and, by no means least important, on which computer the services associated with the domain are to be found. The most important data about the domain and its holder as well as its other administrative and/or technical contacts are publicly accessible through a function known as the whois query. The information on the computer addresses belonging to each of the .de domains is held on so-called name servers and made available round the clock worldwide on the Internet. That is a precondition for services such as e-mail and homepages to be reached and used from everywhere in the world. The same applies for the ENUM domains.

The acronym DENIC is derived from the German for “German Network Information Centre” (i.e. DEutsches Network Information Center). DENIC has the legal form of a cooperative (that's what the letters “eG” after its name mean). It was set up in 1997 and it has its headquarters in Frankfurt am Main. DENIC membership is open to anyone who administers domains under .de for others and who satisfies a number of other conditions. DENIC works on a non-profit basis and accomplishes its tasks in accordance with the internationally recognized guidelines for domain administration for the benefit of the whole German Internet Community.

Since not all .de DNS servers answered queries wrongly, and due to the fact that not every name resolution that includes a “.de” domain name queries the DENIC DNS servers for “.de”, not every user and not every name request (e.g., while browsing a web server) has been affected.

The DNS system makes extensive use of query-reply caching, so correct data for a domain name may still be available in the cache from a name resolution process.

Without this cached information, however, a user or process would wrongly have gotten the information, that the domain was not existent, resulting in interruptions of the used service (web, email, etc.)

In a web browser context, domains resolved to “not existent” trigger an error message of the actual web browser, indicating that the domain name in question does not exist or may have been spelled wrong.

Depending on the application, the domain name in question might have incorrectly been reported as “free” or “available”.

Depending on the Internet service provider used, web users might have been redirected to search engines or portals.

 Domains are an addressing technique for identifying and localizing computers (or "hosts") in the Internet. Computers recognize one another solely by means of their IP addresses, which are purely numerical. The IPv4 standard, which is still the dominant one, requires them to be in the form xxx.xxx.xxx.xxx, where each xxx stands for a number between 0 and 255. A typical IP address might, for instance, be 10.136.66.12. When one computer wants to communicate with another one via the Internet, it sends it "Internet packets" which are addressed to the recipient's IP address.

It is human nature that we usually find it a lot easier to memorize terms and descriptions than rows of figures. That was the reason the Domain Name System (DNS) was developed and it makes it possible to use words, names and terms instead of digits more or less at will (although a few rules have to be complied with). That now makes it possible for Internet users to access hosts either through their IP address or by entering the domain. The DNS can also be used for calling other services and information.

When a domain is called in the Internet, special computers, known as name servers, assume the task of translating it into the corresponding IP address. Because each domain and each IP address is unique, they can both only be registered once in the world.

The DNS itself has a hierarchical structure. A number of Top Level Domains (TLDs), such as .de or .com, are defined as its topmost layer. Under these TLDs, it is possible to register second-level domains, which are nearly always referred to simply as "domains". DENIC administers those domains that come under the Top Level Domain .de.

In certain circumstances, emails will not be delivered. In case the sender address domain allegedly does not exist, emails might be designated as spam and tagged or deleted.

In case the receiver’s domain name is affected by the faulty “NXDOMAIN” responses, handling in the Internet email systems is the same as with a mistyped receiver address: The email’s sender usually gets notified that the address in question does not exist, and that the email could not be delivered.

This happens in most cases (hence “usually”), where protocol compliant email systems are being used, and where the error message can be delivered to the sender’s email address (which could be affected by the above problem, too). Since the delivery of the error message is in most cases local to the sender’s systems – and needs no external domain lookup, possibility of this delivery can be assumed.

In case the receiver of the email validates the sender address for spam averting reasons, and the sender domain is deemed to be non existent, the email may be classified as spam and be rejected. Since this usually happens in the delivery process itself, the sender can be assumed to receive an appropriate error message from their own (outgoing) mail servers.

12 of the 16 locations for .de-nameservers delivered the incorrect NXDOMAIN-answers described. The servers “s.de.net” and “c.de.net” always answered correctly.  The same is true of the IPv6-nameserver in Frankfurt (f.nic.de).

DNS is an important component of the internet, upon which many other services build.  Therefore, it is perceiveable that other services, such as SIP, were affected.  It is barely possible to list all conceivable consequences, so we concentrated on the most important ones in these FAQs.

No. DENIC operates two redundant and independent data centres in Amsterdam (NL) and Frankfurt (D).  On May 11, a scheduled switch of the active data centre from Amsterdam to Frankfurt took place. Since it could not be guaranteed that in the scope of this switch the services offered by these Registry Service Locations (RSLs) would not suffer short interruptions, the switch was officially announced, http://www.denic.de/denic-im-dialog/mailinglisten/public-l.html?url=msg04446.xml.

The nameservice, in contrast, is provided at 16 locations world wide, including Amsterdam and Frankfurt, but is set-up independently of the registry service infrastructure.  Hence, DNS service was not affected by the switch of the RSLs.

No. DNSSEC is a protocol extension of the DNS that protects against certain forms of data falsification.  DENIC is currently operating a DNSSEC testbed to evaluate this technology.  For this purpose, a signed version of the .de-zone is offered on a separate infrastructure. The productive .de-zone is not signed with DNSSEC and an impact of the testbed on the productive environment is impossible. The incorrect answers are not associated with DNSSEC.

No. The protocol extension DNSSEC protects the DNS-data against change and falsification, in particular on the way from the authoritative nameservers, such as DENIC operates, to the resolvers and end systems.  DNSSEC is not capable of recognising or preventing errors in the initial distribution of the data to the nameservers.

It cannot be ruled out that queries have been diverted. This is actually depending on the settings of the respective Internet Service Provider.

 The Top Level Domains (TLDs) are the highest hierarchical level in the international Domain Name System (DNS). They are found at the end of the Domain, to the right of the last dot. We make a distinction between general or generic TLDs (gTLDs), such as .com, .net and .org, and country code TLDs (ccTLDs), such as .de (Germany) or .ch (Switzerland).

Currently, there are 15 gTLDs. Domains for some of them can be registered by anybody, whereas for others, such as .gov, .int, .aero or .museum, registration is reserved for particular user groups (in the four cases listed: the US government, international organisations, companies and institutions concerned with aviation, and museums). The coordination of the gTLDs is in the hands of the international organization ICANN.

The individual ccTLDs are administered by so-called Network Information Centers (NICs). For Germany, that is DENIC. A list of all the existing domain endings and the registries that administer them can be found on IANA's website.

Generally speaking, other TLDs have not been affected. However, the DNS is a widely branching, shared and redundant system, where multiple DNS servers are used for each domain’s name resolution process. Domains solely handled by DNS servers affected by the disturbance would have been affected in the way that no data (IP addresses for web and email servers, etc.) could have been ascertained. This would have lead to the non-availability of services to these domains and services therein.

No.  The problem described in http://blog.1und1.de/2010/05/13/routingprobleme-am-vatertag/ was independent of the DNS disturbance discussed here.

 A general distinction is made between generic Top Level Domains (gTLDs), such as .com, or .info, and country code Top Level Domains (ccTLDs), such as .de.

 You will find information about the gTLDs on the website of the international organization ICANN.

The website of IANA gives you an overview of the more than 240 ccTLDs that exist today. Here, you also find a list of the names and addresses of the registries in charge of each ccTLD.

Many registries make information about domains and domain holders publicly available through a so-called whois search. For many of the gTLDs, you can use the whois search offered by Internic. If this is not possible, please contact the particular registry in charge of the TLD you are interested in to get further information.

 The European Commission decided, as a means of encouraging e-business in Europe and to support the creation of a own European Internet identity, to establish the Top Level Domain .eu. The organization EURid, which was set up jointly by the national registries for .be, .se and .it, has been chosen as the .eu registry.

 No. DENIC is only responsible for the registration of domains under the Top Level Domain (TLD) .de (for Germany). The second-level domain "beispieldomain.de.vu" has nothing to do with the Top Level Domain .de, but is a domain under the county code TLD .vu (which stands for Vanuatu). DENIC has nothing at all to do with the registration of this domain.