Methods and system for routing communication between a client computer and network servers on a data communication network. In response to a request from a web server on the network to authenticate a user of the client computer, an authentication network server directs the client to a user interface network server. The user interface server provides a user interface to the user requesting login information. The authentication server, which is in a different domain than the user interface server, receives and validates the login information. The authentication server further provides a cookie to the client computer if the information retrieved from the user is valid. The cookie has a domain attribute corresponding to the domain of the authentication server.