This page lists the ACSC’s publications on security domains and trust boundaries. Introduction to Cross Domain Solutions This publication introduces technical and non-technical audiences to the concept of a Cross Domain Solution (CDS), a type of security capability that is used to connect discrete systems within separate security domains in an assured manner. Fundamentals of Cross Domain Solutions This guidance introduces technical and non-technical audiences to cross domain security principles for securely connecting security domains. It explains the purpose of a Cross Domain Solution (CDS) and promotes a data-centric approach to a CDS system implementation based on architectural principles and risk management. This guidance also covers a broad range of fundamental concepts relating to a CDS, which should be accessible to readers who have some familiarity with the field of cyber security. Organisations with complex information sharing requirements are encouraged to refer to this guidance in the planning, analysis, design and implementation of CDS systems. Implementing Network Segmentation and Segregation This publication intends to assist staff responsible for an organisation’s network architecture and design to increase the security posture of their networks by applying network segmentation and segregation strategies.