Which aspect is crucial during dynamic application security testing?

During dynamic application security testing, running tests while the application is functioning is crucial. This aspect is essential because dynamic testing involves evaluating an application in its operational state, which provides insights into how it behaves during real-time execution. By analyzing the application while it is running, testers can identify security vulnerabilities and issues that may not be detectable through static analysis, such as input validation problems, authentication weaknesses, and security configurations.

Dynamic testing allows for a more comprehensive understanding of the application's behavior under various conditions. This includes testing for potential security threats that may arise from user interactions or external inputs, which can be critical in identifying risks that impact the application's overall security posture. By focusing on the application's live performance, developers and security professionals can better address vulnerabilities before the software is deployed or during its usage.