DomainUser class

DomainUser

 public static class DomainUser
    {
        /// <summary>
        /// Method return true if user is domain user or false if is not domain user. Method return null if program run as local user
        /// </summary>
        /// <param name="username"></param>
        /// <param name="domainServerName"></param>
        /// <returns></returns>
        public static bool? IsDomainUser(string username, string domainServerName)
        {
            
            if (!IsCurrentUserDoaminUser())
            {
                return null;
            }
            

            var entry = new DirectoryEntry(string.Concat("WinNT://", domainServerName));
            foreach (DirectoryEntry child in entry.Children)
            {
                if (child.SchemaClassName != "User") continue;
                if (String.Equals(child.Name, username, StringComparison.CurrentCultureIgnoreCase))
                    return true;
            }
            return false;
        }

        /// <summary>
        /// method return true if program run as domain user or false if run as local user
        /// </summary>
        /// <returns></returns>
        private static bool IsCurrentUserDoaminUser()
        {
            return Environment.MachineName != Environment.UserDomainName;
            
        }
    }