In this case the printer typically provides two LPD queues. It is typically this second queue that is more use. We can set up two queues on lpd-serv.cam.ac.uk , one for each. In this case our server interprets any PostScript errors and emails them back to you. Port 515 is the LPD service and port 9100 is the JetDirect service.
Many printers support both interfaces.
If the probing output says that all ports were closed then you have a printer that has been configured to restrict who can access it. There are a number of constraints on queue names which we impose to make the queue name acceptable over as wide a range as possible of Unix printing systems. The name must have 14 or fewer characters. The name must be composed of lowercase letters, digits and underscores. There must be no adjacent underscores.