Network administration is a task that requires experience in relating symptoms of network problems with possible causes and corrective actions. We describe the design of a system and more specifically its information retrieval component, which aims to retrieve articles relevant to a given problem case from a collection of articles describing previously solved problems and their associated solutions. An article is described by a term vector. We present a methodology for defining the vocabulary and preliminary results for assessing the quality of expert-proposed modifications to the vocabulary. We obtain vocabulary-derived document classes from a self-organising map and assess vocabulary quality using the quality of classification into these classes.