Confidentiality ensures that data is protected from unauthorized access and is only available to users, systems, or processes that are permitted to view it.

A reflected denial of service (RDoS) attack is a type of DDoS attack that uses spoofed source IP addresses to send requests to a third-party server, which then sends responses to the victim server. The attacker exploits the difference in size between the request and the response, which can amplify the amount of traffic sent to the victim server. The attacker also hides their identity by using the victim's IP address as the source. A RDoS attack can target DNS servers by sending forged DNS queries that generate large DNS responses. This can flood the network interface of the DNS server and prevent it from serving legitimate requests from end users.

To reduce the number of individual operating systems while decommissioning physical servers, the company should use containerization. Containerization allows multiple applications to run in isolated environments on a single operating system, significantly reducing the overhead compared to running multiple virtual machines, each with its own OS.
Containerization: Uses containers to run multiple isolated applications on a single OS kernel, reducing the need for multiple OS instances and improving resource utilization.
Microservices: An architectural style that structures an application as a collection of loosely coupled services, which does not necessarily reduce the number of operating systems.
Virtualization: Allows multiple virtual machines to run on a single physical server, but each VM requires its own OS, not reducing the number of OS instances.
Infrastructure as code: Manages and provisions computing infrastructure through machine-readable configuration files, but it does not directly impact the number of operating systems.

A digital certificate enables both encryption (confidentiality) and digital signatures (integrity), providing strong cryptographic protection for data.