This guidance provides an introduction to the key topics to consider when designing, maintaining, or using networks that need to be secure and resilient. Establish, implement, and actively manage (track, report on, correct) the security configuration of network infrastructure devices using a rigorous configuration management and change control process in order to prevent attackers from exploiting vulnerable services and settings. Networks are fundamental to the operation, security and resilience of many organisations. Zero Trust is a security. Securing network devices is essential for preventing unauthorized access and maintaining network integrity.