Duress: A condition in which a person performs an act as a result of violence, threat, or other pressure against the individual. In the legal context, duress can make a contract voidable if one party involuntarily agrees due to the wrongful threat of the other party. In security terms, a duress code is a covert signal used by an individual to indicate they are in danger without alerting the potential aggressor, commonly used in security systems and protocols where silent alarms or emergency signals are necessary.

Dynamic Analysis: A method used in software testing where programs are executed in real-time to identify potential defects or errors. Unlike static analysis, which is performed without running the code, dynamic analysis tests the software's behavior under various conditions and inputs to find issues such as memory leaks, race conditions, or security vulnerabilities. It is an essential part of the quality assurance process, being able to simulate actual operating conditions and user interactions.

Dynamic Application Security Testing (DAST): A security testing method that analyzes a live application in its operating environment to identify vulnerabilities from an external attacker's perspective. This testing focuses on detecting security flaws, misconfigurations, and weaknesses exploitable by malicious actors, and is generally conducted in the later stages of development or in production.

Dynamic Host Configuration Protocol (DHCP): A network management protocol used on IP networks where a DHCP server dynamically assigns an IP address and other network configuration parameters to each device on the network so they can communicate with other IP networks. DHCP eliminates the need for manually assigning IP addresses to all network devices, simplifying the process of connecting devices to the network and managing the allocation of IP addresses within a network.

Dynamic Link Libraries (DLLs): Modular files containing code and data that can be used by multiple applications simultaneously. DLLs allow for code reuse, modularization, and memory efficiency as the same library can serve multiple applications, reducing the need for redundant code. Their misuse or manipulation could lead to potential security vulnerabilities such as DLL hijacking or injection.

Dynamic Packet Filtering: A security measure used in network firewalls to manage the flow of network traffic in real-time. Unlike static packet filtering, which only examines a packet based on predefined rules, dynamic packet filtering evaluates packet information within the context of the packet's state or connection, providing a more adaptive and sophisticated approach to network security.