A valid domain name character is that which contains a set of alphanumeric ASCII characters (i.e., a-z, A-Z), numbers (i.e. 0-9) and dashes (-) or a combination all of these. It’s a domain name that has the valid characters and length. It mostly has a minimum of 3 and a maximum of 63 characters.
Characters & valid characters' lengths for Domain names
For domain names to be valid, domain names MUST:
have a minimum of 3 and a maximum of 63 characters;
begin with a letter or a number and end with a letter or a number;
use the English character set and may contain letters (i.e., a-z, A-Z), numbers (i.e. 0-9) and dashes (-) or a combination of these;
neither begin with nor end with a dash (-);
not contain a dash in the third and fourth positions (e.g. www.ab- -cd.com);
not include a space (e.g. www.ab cd.com);
not include underscore (e.g www.ab_cd.com)
Note: The registration of 2-character and single character domains is yet to be open up to the general public and are all tagged as premium domain names which are highly costly and you may not necessarily wait for a bidding process as it could be obtained at the Buy Now Bid price.
Most African ccTLDs require a minimum of 4 characters before they can be registered.
Some domains may require additional documentation before they can be registered and it can take more than a week to be registered.