As the CISO, in order to ensure system availability I would implement redundancy and failover mechanisms to prevent downtime in case of hardware failures, alongside a disaster recovery plan to swiftly restore operations after major disruptions. DDoS mitigation strategies and load balancing would protect against traffic overloads and malicious attacks, while high availability architectures minimize the risk of single points of failure. Regular patch management and real-time monitoring would help identify and address potential issues proactively. Additionally, strict service-level agreements with vendors and network segmentation would ensure critical systems are isolated and protected.