Regular Expressions 101

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x

(sub)domain match

Open Workspace
  • PCRE (Legacy)
  • Match
0

Regular Expression

/
(?!.{253})((?!-)[A-Za-z0-9-]{1,63}(?<!-)\.){1,126}+[A-Za-z]{2,6}
/

Description

1.Tree of subdivisions may have up to 127 levels. 2.Each label may contain up to 63 characters.
3.The full domain name may not exceed the length of 253 characters in its textual representation.

rfc1035 rfc1123 rfc2181

Submitted by Nick Chkhikvishvili