Students bring prior knowledge to their learning experiences. This prior knowledge is known to affect how students encode and later retrieve new information learned. Teachers and content developers can use information about students' prior knowledge to create more effective lessons and materials. In many content areas, particularly the sciences, there is extensive research about the conceptions and misconceptions students bring to the learning environment. This research has used tools ranging from instructor and student interviews to written assessments to identify these ideas. In addition, concept maps have been explored as a way to understand how students relate different concepts to each other. A difficulty with concept maps is that there are not good solutions for studying larger groups of students, but also maintaining the detail to see how specific concepts are related. One way to address this is with similarity ratings and the use of the Pathfinder network program. Although there are some areas in which a large amount is known about students' knowledge, there is little understanding of either student or instructor knowledge in the field of computer networking. This paper is a preliminary attempt to explore the knowledge structures of students entering a computer networking class and their instructors using the Pathfinder network methodology. The study participants consisted of 156 students and 12 teachers in 12 different classes, each at a different institution. All of the students were enrolled in the first course (Cisco Certified Networking Associate 1) in the Cisco Networking Academy Program. Students and instructors rated the similarity between pairs of words that represented concepts covered in the course prior to beginning instruction in the course. There were two different groups of words, one representing the course as a whole and one representing a specific chapter. The similarity ratings for these terms were submitted to Pathfinder network analysis, creating both average concept maps for students and instructors as well as measures of the similarity between the maps. Analysis of the maps revealed an instructor map that corresponded to the OSI model, a model of networking. The corresponding student map indicated students did not have this conceptualization of how the theoretical layers of the model work. Instead, students tended to link things that might generalize as equipment, and words that sounded similar. This linking of equipment was further demonstrated in the analysis of concepts from the chapter that introduces basic networking concepts. Whereas instructors exhibited an organization by network type (local or wide-area), the students displayed an equipment-centric organization. The instructor networks provide initial information about how experts organize knowledge in this relatively young field. By understanding some of the ways that students understand concepts prior to instruction, teachers should be better able to focus and tailor instruction. (Contains 2 figures and 1 table.)