regular expression for the address of domain name server

Question

I want to create a regular expression for DNS.

My requirement is that the valid DNS should be:

Only 4 dots(.) are allowed. I have tried this regular expression but its not working. Please suggest.

^[a-zA-Z0-9]+.[a-zA-Z0-9]+.[a-zA-z0-9]+.[a-zA-z0-9]$

once I ve found this beautidul service, it may help. http://www.debuggex.com/ — StNickolas, Jun 25 '13 at 11:07
`.` is usually a special character that matches any character. You probably need to escape it since you want a `.` and not the meta-character. — BLaZuRE, Jun 25 '13 at 11:08
@StNickolas That is an amazing website. +1 for pointing that out. — BLaZuRE, Jun 25 '13 at 11:10
@anonymous will [this link](http://stackoverflow.com/questions/2063213/regular-expression-for-validating-dns-label-host-name) help? — 1ac0, Jun 25 '13 at 11:10

Matten · Accepted Answer · 2013-06-25T11:27:46.520

1

A very simple regex could be something along

^www\.[a-zA-Z0-9]+\.[a-zA-Z0-9]+(\.[a-zA-Z0-9]+(\.[a-zA-Z0-9]+)?)?$

Three points:

the point (.) is a special character and must be escaped (\.)
we need optional clauses for the last two sections.
your examples start with www, so you need to include this in order to use the start mark (^)

edited Jun 25 '13 at 11:27

answered Jun 25 '13 at 11:09

Matten

score 1 · Answer 2 · edited May 23 '17 at 10:32

1

try this link

edited May 23 '17 at 10:32

Community

answered Jun 25 '13 at 11:30

Ran Adler

Evgeniy Dorofeev · Answer 3 · 2013-06-25T11:21:49.323

0

try this

str.matches("www(\\.\\w+){2,4}")

edited Jun 25 '13 at 11:21

answered Jun 25 '13 at 11:11

Evgeniy Dorofeev

score 0 · Answer 4 · answered Jun 25 '13 at 11:17

0

try this regex

^(www\.|)(([a-zA-Z0-9])+\.){1,4}[a-z]+$

answered Jun 25 '13 at 11:17

StNickolas

4 Answers4