Minimum characters in a subdomain?

[dude]

Hello,

Is it possible to have a single letter subdomain?

For example -

a.irishwebmasterforum.com

Or is there a two or three character minimum?

Thanks

The Dude

 

[mneylon]

It's a subdomain / A record so the only restrictions are those imposed by your DNS software!

 

[dude]

Great, thanks

 

[kae]

yes, it is possible. as far as I know, the restrictions on a domain name are that the first and last characters (even if they are one and the same) must be a letter or a number, and the characters in between (if there are any) must be letters, numbers or hyphens.

an example of a famous one-letter subdomain: X.Org Foundation (.org is the top-level domain, and x is a subdomain of that).

 

[mneylon]

an example of a famous one-letter subdomain: X.Org Foundation (.org is the top-level domain, and x is a subdomain of that).

x.org is not a subdomain. It's a second level domain.

 

[kae]

nope. x.org is a subdomain of org.

From RFC 1034:
"A domain is identified by a domain name, and consists of that part of
the domain name space that is at or below the domain name which
specifies the domain. A domain is a subdomain of another domain if it
is contained within that domain. This relationship can be tested by
seeing if the subdomain's name ends with the containing domain's name.
For example, A.B.C.D is a subdomain of B.C.D, C.D, D, and " "."

so as an example, X.Org Foundation is a subdomain of x.org, which is a subdomain of org (which is a subdomain of " ").

See section 3.4 for an example which states that .mil, .edu and .arpa (as examples) are subdomains.

 

[jmcc]

The obvious eample for single character subdomains would be these:
g.gtld-servers.net.
h.gtld-servers.net.
i.gtld-servers.net.
j.gtld-servers.net.

Regards...jmcc