Show pagesourceBack to top Share via Share via... Twitter LinkedIn Telegram Yammer RedditRecent ChangesSend via e-MailPrintPermalink × Regular Expressions Common regexes purpose/match/validates Regex FQDN1,2 (?=^.{1,254}$)(^(?:(?!\d|-)[a-zA-Z0-9\-]{1,63}(?<!-)\.?)+(?:[a-zA-Z]{2,})$) online tools Regexr – evaluates and explains regular expressions Regexpal – evaluates regexes Regex101 – online RegEx IDE Regex Crossword – game to learn regular expressions [1] fully qualified domain name [2] from http://blog.gnukai.com/2010/06/fqdn-regular-expression/ which references RFC1035 Last modified: 2021-12-15 11:17