If you’re about to embark on a requirements drill or needs assessment focused on “web GIS,” it is important to be sure to answer one question as you proceed: Do you actually need any specialized mapping server at all?
If “none” isn’t one of the choices in your analysis of alternatives, then you are doing it wrong in 2014 and you may be doing a disservice to your users. The state of current technology makes it perfectly feasible to publish interactive mapping products as static content, using nothing more than your current web server. Given the complexity of today’s IT environments, including requirements for FISMA compliance on Federal systems, it is irresponsible not to consider this option before recommending yet another specialized server product (or hosted cloud solution) for your user’s IT architecture.