Out of curiosity, does anyone know what's the maximum length (in characters) for a domain name?
Let's exclude the http://www.
I know the maximum length of an url is about 2000 chars. But here I'm more ineterested in just the domain part or the url.
On Wikipedia they say: "The full domain name may not exceed a total length of 253 characters in its external dotted-label specification." But what does that mean?
253 characters is the maximum length of full domain name, including dots: e.g. www.example.com = 15 characters.
63 characters in the maximum length of a "label" (part of domain name separated by dot). Labels for www.example.com are com, example and www.
This is an example of the domain with longest possible label (it leads to a scammy site): http://www.abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijk.com/. The domain name length = 71 characters.
This will be an example of longest domain name: abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcde.abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijk.abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijk.abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijk.com
It depends on what you want to do with the domain really.
For a domain just used as a website, the limit is 255 characters. Source: RFC2821 (April 2001) established this and RFC5321 (October 2008) retained this standard. To quote both of them...
4.5.3.1.2. Domain
The maximum total length of a domain name or number is 255 characters.
For a domain that works with emails, the limit is 253 characters. Source: See the requirements of local-parts (i.e., the user in user@example.com) from RFC821 (August 1982), page 29. This limit is imposed because the to field in e-mails cannot exceed 255 characters, one of those characters must be @, and the local-part must be at least one character long (i.e., a@(253-character-domain), which hits the SMTP 255 to-field limit).
