What restrictions are there on what I can register as a domain name?

There are some basic rules that apply to domain names, mainly concerning length, characters, punctuation, and formatting. However, specific requirements may vary depending on the domain extension (TLD), such as .com, .org, or country-code domains.

The general rules are:

• Domain names can contain letters, numbers, and hyphens (-) in their labels. Standard DNS labels use ASCII letters (a–z), numbers (0–9), and hyphens. Internationalized domain names (IDNs) allow additional characters from many languages through a separate encoding system.
• A domain name label cannot begin or end with a hyphen.
• A single domain label (the part between dots) can generally contain up to 63 characters (technically 63 octets in DNS).
• A complete domain name (including all labels and extensions) can generally be up to 253 characters long when written in its normal form, excluding the final root dot. The DNS limit is 255 octets, including the terminating root label.
• Domain names are not case-sensitive; uppercase and lowercase letters are treated the same.
• Domain names cannot contain spaces.
• Domain names can begin with numbers, unless a specific domain extension has additional restrictions.
• Two-character domain names are allowed in many domain extensions, although availability depends on the registry, restrictions, and whether the name has already been registered.
• Some domain extensions have additional rules, such as minimum length requirements, restrictions on allowed characters, reserved names, or eligibility requirements.

In addition, internationalized domain names (IDNs) allow the use of characters from many languages. These characters are converted into a standardized ASCII-compatible format (called Punycode) for use within the DNS system.

You can use a wide variety of letters, numbers, words, and phrases to create your domain name, provided the name follows the rules of the relevant domain extension, is available for registration, and does not violate registry policies, trademark rules, or other legal restrictions.

Article ID: 151
Created On: Thu, Mar 5, 2015 at 4:20 PM
Last Updated On: Tue, Sep 8, 2026 at 5:41 PM

Online URL: https://www.heartinternet.uk/support/article/what-restrictions-are-there-on-what-i-can-register-as-a-domain-name.html