Internet Explorer does not accept cookies from certain domain names

A user opens a webpage from http://servername.xxx.yy. The web site at that address sets a cookie and specifies "xxx.yy" as the domain for that cookie.  However, Internet Explorer does not save the cookie information.

For security reasons, Internet Explorer does not save cookie data for domains like xxx.yy, where .yy is a two-letter country code domain and the three letters xxx are one of the generic top level domain names: com, edu, gov, int, mil, net, or org.  Domains of this form are treated as top level domains, effectively a country-specific version of the generic top level domain.  For security reasons, wininet prevents setting cookies for such domains.  In this case, xxx.yy is effectively a top level domain, and is protected in the same way as ".com" would be.

This behavior is by design.

Following is a sample scenario:

1. A user opens Internet Explorer 6.0, 7.0, or 8.0 and browses to http://contoso.gov.hu
2. Client-side script in the web application at http://contoso.gov.hu calls document.cookie = "name=value;domain=gov.hu" to set a cookie.
3. The cookie is not saved on the user's machine.  In this case, gov.hu is recognized as an effective Top Level domain.

For more information about Generic Top-Level Domains, please see:

Top Level Domains
http://www.icann.org/en/tlds/

For more information on Internet Explorer and two-letter domains, please see: 

Internet Explorer does not set a cookie for two-letter domains
http://support.microsoft.com/default.aspx?scid=kb;EN-US;310676

For more information on the HTTP State Management Mechanism, please see:

HTTP State Management Mechanism
http://www.ietf.org/rfc/rfc2109.txt