Get User List from Active Directory

class ActiveDirectory
    {
        public ActiveDirectory()
        {
            //PrincipalContext insPrincipalContext = new PrincipalContext(ContextType.Machine); //Connecting to local computer.
            //PrincipalContext insPrincipalContext = new PrincipalContext(ContextType.Domain, "MPTDC1-INDIA", "DC=MPTDC1-INDIA,DC=com"); //Connecting to Active Directory
            //PrincipalContext insPrincipalContext = new PrincipalContext(ContextType.Machine, "TAMERO", "administrator", "password"); //Connecting to local computer with credentials of an user

        }

        public void GetUsers()
        {
            PrincipalContext insPrincipalContext = new PrincipalContext(ContextType.Domain, "MPTDC1-INDIA");

            UserPrincipal insUserPrincipal = new UserPrincipal(insPrincipalContext);
            insUserPrincipal.Name = "*";
            SearchUsers(insUserPrincipal);
        }

        private void SearchUsers(UserPrincipal parUserPrincipal)
        {
            PrincipalSearcher insPrincipalSearcher = new PrincipalSearcher();
            insPrincipalSearcher.QueryFilter = parUserPrincipal;
            PrincipalSearchResult<Principal> results = insPrincipalSearcher.FindAll();
            foreach (Principal p in results)
            {
                Console.WriteLine(p.DisplayName);
            }
        }
    }

class Program
    {
        static void Main(string[] args)
        {
            var ad = new ActiveDirectory();
            ad.GetUsers();
        }
    }