WebSphere Application Server V6.1 separates the server user identity from the primary administrative user. The primary administrative user is any valid user in the user account repository that you choose to give default administrative privileges. The server user identity is used for server to server communication. By selecting the automatically generated server identity, WebSphere creates an identity for internal communications that is not stored in the repository and does not have a password. LDAP directories still require a bind DN for successful communications.
WAS will ask you for the sever user identity while configuring user repository