Domain Name Valid Characters. The domain name should be a-z or A-Z or 0-9 and hyphen -. Character Valid Domain Name Character.
The domain name should be a-z or A-Z or 0-9 and hyphen -. But some records have stricter rules for either the owner name andor the resource data RDATA. Unfortunately special characters like _ are not allowed.
Have a minimum of 3 and a maximum of 63 characters.
The domain name should be a-z or A-Z or 0-9 and hyphen -. But some records have stricter rules for either the owner name andor the resource data RDATA. - the name can neither start nor end with the character - although the character - is allowed inside the name. Though originally intended for use by for-profit business entities for a number of reasons it became the main TLD for domain names and is currently used by all types of entities including nonprofits schools and private individuals.