Network Defense Essentials (NDE) 2025 – 400 Free Practice Questions to Pass the Exam

The mechanism that ensures that only one person can enter after authentication in a secure environment is a mantrap. A mantrap is a small room or space that serves as a secure entry point, typically between two doors. When one door is closed, it prevents another person from entering until the person inside the mantrap has authenticated their identity and exited or entered the next door.

Mantraps are designed to enhance security by controlling the flow of individuals into a secure area. They can also include access control features such as biometric scanners or keycard readers, providing an additional layer of verification. The design restricts access, ensuring that only one person can enter or exit at any given time, thereby minimizing the risk of unauthorized access or tailgating.

In contrast, the other options—such as an emergency exit or security screening—do not specifically address the issue of controlling access to ensure that only one authorized individual can enter at a time. Keycard access can certainly facilitate authentication but does not inherently restrict entry to one person at a time without the additional control provided by a mantrap.