true if the specified username and password are valid; otherwise, false.
Takes, as input, a user name and a password and verifies that the values match those in the data source. MembershipProvider.ValidateUser(string, string) returns true for a successful user name and password match; otherwise, false.
For successful validations, MembershipProvider.ValidateUser(string, string) updates the MembershipUser.LastLoginDate for the specified user.