How to validate a domain name using Regex & Php?

Question

Hi,

I want a solution to validate only domain names not full urls, The following example is what i'm looking for:

domain.com -> true
domain.net/org/biz... -> true
domain.co.uk -> true
sub.domain.com -> true
domain.com/folder -> false
domµ*$ain.com -> false

Thank you

Answer 1

How about:

^(?:[-A-Za-z0-9]+\.)+[A-Za-z]{2,6}$

Answer 2

Remember, regexes can only check to see if something is well formed. "www.idonotexistbecauseiammadeuponthespot.com" is well-formed, but doesn't actually exist... at the time of writing. ;) Furthermore, certain free web hosting providers (like Tripod) allow underscores in subdomains. This is clearly a violation of the RFCs, yet it sometimes works.

Do you want to check if the domain exists? Try dns_get_record instead of (just) a regex.