Double-Blind Test in Penetration Testing: This form of assessment simulates a real-world attack on a system, network, or application, where the defenders are unaware of the simulated attack just as they would be in an actual attack. It provides an organization with the most realistic indication of its security posture and readiness without providing prior knowledge of the testing scenario to its security personnel.

DREAD: An acronym for Damage, Reproducibility, Exploitability, Affected Users, and Discoverability, DREAD is a risk assessment model used to quantify, compare, and prioritize the risk levels of security vulnerabilities in a system. It helps stakeholders to understand the potential risk of a vulnerability and to make informed decisions about mitigations.

Dry Pipe Fire Extinguisher System: A fire suppression system where pipes are filled with pressurized air or nitrogen instead of water, used in environments prone to freezing. Upon activation by a fire, the air pressure drops, allowing water to fill the pipes and be discharged through sprinkler heads to extinguish the fire. This design prevents water from freezing in the pipes and causing damage.

Dual control: A security principle that requires two or more authorized individuals to perform a specific task. It reduces the risk of fraudulent or unauthorized activity as it necessitates the collaboration of two separate entities to execute the action. It is commonly used in high-risk operations or when handling sensitive information.

Dual Custody: Dual custody requires two or more individuals to access sensitive resources. This practice enhances security by ensuring that no single individual can access, manipulate, or transport sensitive data or assets. It's often applied to financial transactions, system administrative tasks, or secure facilities access.

Dual-Homed Host/Firewall: A security component that serves as a bridge between two networks, typically a secure internal network and an unsecured external network like the Internet. The dual-homed host has two network interfaces, with each connected to a separate network. It manages and controls the flow of traffic between these networks, mitigating the risk of unauthorized access or data breaches.