A top-level domain (TLD) is the ending of an Internet address. It is the highest hierarchy level in the international Domain Name System (DNS) and identifies the part of the domain after the last right-hand dot. At www.nic.koeln, the ending .koeln therefore denotes the top-level domain.

A distinction is made between two groups of TLDs:

• the country-specific top-level domains, known as ccTLDs (country code TLD), are endings such as .at for Austria or .de for Germany.
• the general or generic top-level domains (= gTLDs).
  These are endings such as .com for commercial websites or .org for non-profit offerings. These long-standing domain endings have been expanded to include a large number of additional gTLDs: In addition to .koeln/.cologne, there are currently (as of January 2025) domains in Germany with the regional ending .berlin, .nrw or .hamburg for example, while city endings such as .london, .paris, .nyc and .amsterdam are available internationally. There are also many other general top-level domains such as .shop, .hotel or .reise.

The ICANN (Internet Corporation for Assigned Names and Numbers) is the central global Internet administration organisation. It is a non-profit organisation under US law with its headquarters in Los Angeles, California.

As a network management organisation, it coordinates the technical aspects of the Internet. Representatives of governments and a large number of interest groups (companies, Internet users, technicians, etc.) ensure ICANN's independence and neutrality (multi-stakeholder model) and jointly develop guidelines for the global administration of the domain name system.

The tasks of ICANN include

• Deciding on the basis for the administration of top-level domains,
• coordinating the root servers through which the individual top-level domains are addressed on the Internet,
• and the allocation of IP address ranges to continental registrars via the sub-organisation IANA.

The abbreviation IDN stands for ‘Internationalised Domain Name’. These domains contain umlauts, diacritical characters or letters from alphabets other than the Latin alphabet (for more details, see Wikipedia).

IDNs are converted for correct processing - e.g. the domain stärke.at then becomes xn--strke-hra.at. You can try out what your IDN looks like with an IDN converter.

For IDNs under .koen/.cologne, the characters of the ‘Latin script’ (LATIN SCRIPT) can be used.

There are restrictions, but these hardly limit their creativity in finding names.

Firstly, the framework conditions are defined by the registry's business policy.

In addition, the registration of third-party brand names, company names or names, for example, can lead to injunctive relief against the holder of the stronger right, who can then also insist on the surrender of the domain. It is therefore advisable to research whether such a right to a domain could exist before registering.

To find out who owns a domain, please contact the registrar with whom the domain was registered. You can find out which registrar this is in the WHOIS. 

The Registration Data Access Protocol (RDAP) is the successor to WHOIS. Like WHOIS, RDAP provides access to information about Internet resources (domain names, autonomous system numbers, and IP addresses). Unlike WHOIS, RDAP provides:

• A machine-readable representation of registration data
• Differentiated access
• Structured request and response semantics
• Internationalisation
• Extensibility

The registration of a .koeln/.cologne domain name cannot be carried out directly by dotKoeln GmbH. Rather, a registrar/an ICANN-accredited registrar (or its reseller) must be commissioned to do so.

Registering a domain name via a registrar/reseller is like buying a book in a bookshop. A registrar offers services for many different Internet domains, including .koeln/.cologne, just as a bookseller sells books from many different publishers.

The list of ICANN accredited registrars who also have a contract with the .koeln/.cologne TLD and can therefore offer .koeln/.cologne domains can be found here.

A .koeln/.cologne domain name can only consist of numbers (0-9), hyphens and lower case letters (a-z). It may neither begin nor end with a hyphen. If the domain name contains hyphens in the 3rd or 4th position, the name must be a valid translation (ASCII Compatible Encoding) of an IDN code.

The minimum length of a domain is one (1) character, the maximum length is sixty-three (63) characters. If the domain is an IDN, the maximum length is determined by RFC 5890 and RFC 5891.

A domain may be displayed as unavailable for the following reasons:

1. the domain has already been registered.

2. it is a domain name that is blocked due to the requirements of the international domain administration authority ICANN.

3. the domain name is blocked by a trademark owner via BSA - Brand Security Alliance

Premium domains are domain names that are categorised as particularly high quality due to high demand. Like all other .koeln/.cologne domains, these can be registered with registrars, but have a higher (annual) price.

The annual fee for a .koeln/.cologne domain is currently (as of January 2025) €35 - €50, with the final product and pricing being determined by the respective registrar.

It should be noted that the domains are sold by dotKoeln GmbH to all registrars at the same conditions and that they offer additional services of varying scope and quality, such as e-mail services, homepage designers, etc.

The conditions under which a .koeln/.cologne domain can be registered are defined in the Registration Policies.

If the ownership or use of a domain infringes trademark rights, the rights holder has the option of having it blocked for one month directly via the registry (dotKoeln GmbH) (transfer block). Proof of the rights is required for this.

During this period, judicial or extrajudicial measures can be taken to clarify the ownership claims. An extension of the block is possible for a maximum of one further month.

If you have a right to a domain name that someone else has registered under .koeln/.cologne, you can make use of the UDRP procedure (see General Guidelines, Section 14) or sue for your right in a local court.

However, it is recommended to seek an out-of-court solution in advance to avoid unnecessary costs.

When a .koeln/.cologne domain is registered for the first time, there is a transfer lock of 60 days to ensure clear ownership. This means that you can only transfer the domain to another .koeln/.cologne registrar after this period has expired.

Due to the new Data Protection Act (GDPR), which has been in force since May 2018, data of private individuals may no longer be displayed in the WHOIS. To find out who owns a domain, please contact the registrar with whom the domain was registered (shown in the WHOIS).

Legal assistance is not required to register a domain.

However, when it comes to obtaining a domain from another domain holder on the basis of a trade mark or name right, cooperation with a lawyer is recommended.

However, initial contact with the domain holder does not necessarily have to be made via a lawyer, as amicable arrangements can often be reached through direct contact.