Code
DirectoryEntry myDirectoryEntry = new DirectoryEntry("LDAP://" + d);
                DirectorySearcher mySearcher = new DirectorySearcher(myDirectoryEntry);
                mySearcher.Filter = "(&(objectCategory=person)(objectClass=user))";
                mySearcher.SearchScope = SearchScope.Subtree;

                SearchResultCollection searchResult = mySearcher.FindAll();

                foreach (SearchResult result in searchResult)
                {
                    ResultPropertyCollection props = result.Properties;

                    Console.WriteLine(props["name"][0].ToString());
                }