The concept of security within the network environment includes aspects drawn from all operating systems, application software packages, hardware solutions, and networking configurations present within the network to be secured, and from within any network-sharing connectivity directly or indirectly with the network to be secured. For the Security+ exam, you need to develop the broadest set of skills possible, gaining experience from the most specific to the most general of security concepts. This chapter focuses on access control mechanisms and methods for secure network authentication and physical access.