The CookieDomain property value is set in the configuration file for an ASP.NET application by using the domain attribute of the forms configuration element. The CookieDomain property value determines the Domain that the cookie will be used for.
Windows 98, Windows Server 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.