Note: The aspects of the McHugh paper relevant for the prelim concern (1) how to soundly evaluate security systems, (2) the difficulties of constructing sufficiently realistic representations of benign behavior, (3) the issues that arise when attempting to define common metrics for comparison, and (4) how taxonomies can shape one's view of a problem domain. You do not need to concern yourself with the details of how the paper applies these concerns to the specific evaluation of intrusion detection systems.