Can I improve this regex check for valid domain names?

Posted by Josh on Stack Overflow See other posts from Stack Overflow or by Josh
Published on 2008-12-30T10:22:13Z Indexed on 2010/05/17 19:40 UTC
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regex

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dns

So, I have been working on this domain name regular expression. So far, it seems to pick up domain names with SLDs and TLDs (with the optional ccTLD), but there is duplication of the TLD listing. Can this be refactored any further?

params[:domain_name].downcase.strip.match(/^[a-z0-9\-]{2,63}
\.((a[cdefgilmnoqrstuwxz]|aero|arpa)|(b[abdefghijmnorstvwyz]|biz)|
(c[acdfghiklmnorsuvxyz]|cat|com|coop)|d[ejkmoz]|(e[ceghrstu]|edu)|f[ijkmor]|
(g[abdefghilmnpqrstuwy]|gov)|h[kmnrtu]|(i[delmnoqrst]|info|int)|
(j[emop]|jobs)|k[eghimnprwyz]|l[abcikrstuvy]|
(m[acdghklmnopqrstuvwxyz]|me|mil|mobi|museum)|(n[acefgilopruz]|name|net)|(om|org)|
(p[aefghklmnrstwy]|pro)|qa|r[eouw]|s[abcdeghijklmnortvyz]|
(t[cdfghjklmnoprtvwz]|travel)|u[agkmsyz]|v[aceginu]|w[fs]|y[etu]|z[amw])
(\.((a[cdefgilmnoqrstuwxz]|aero|arpa)|(b[abdefghijmnorstvwyz]|biz)|
(c[acdfghiklmnorsuvxyz]|cat|com|coop)|d[ejkmoz]|(e[ceghrstu]|edu)|f[ijkmor]|
(g[abdefghilmnpqrstuwy]|gov)|h[kmnrtu]|(i[delmnoqrst]|info|int)|
(j[emop]|jobs)|k[eghimnprwyz]|l[abcikrstuvy]|
m[acdghklmnopqrstuvwxyz]|mil|mobi|museum)|
(n[acefgilopruz]|name|net)|(om|org)|
(p[aefghklmnrstwy]|pro)|qa|r[eouw]|s[abcdeghijklmnortvyz]|
(t[cdfghjklmnoprtvwz]|travel)|u[agkmsyz]|v[aceginu]|w[fs]|y[etu]|z[amw]))?$/)

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