title: Data annotations extensions validators: Is .c0m a valid TLD
body: <p>I downloaded Data Annotations Extensions for .NET from <a href="http://dataannotationsextensions.org/" rel="nofollow">Data annotations extensions</a> for use to validate user input in an C#/ASP.NET MVC application. The library came with high commendations from the developer community, including those from Stack Overflow. </p>
  
  <p>One of the inputs I am validating is email. The data annotations extensions are treating an email address like <code>noreply@user.c0m</code> as valid - note the <code>0</code> in <code>.c0m</code>. I have been reading up on the validity of a TLD containing a numeric character but I am coming across conflicting information. </p>
  
  <p>Some internet resources suggest that <code>.c0m</code> is a valid TLD while others suggest its not. Others suggest that ICANN might pull (or might have pulled) the plug on them. I would like to get an opinion on the validity or otherwise of such a TLD. Should an email address like <code>noreply@user.c0m</code> be considered valid or should I just ditch the Data Annotations Extensions? </p>