IntroNS Practice Exam

Access control models describe how permissions are granted and enforced on resources. Discretionary access control lets the resource owner decide who can access and with what rights, typically by granting permissions on a file. Mandatory access control relies on system-wide classifications and clearances; access is allowed only when the subject’s clearance matches the object's labeling. Attribute-based access control makes decisions based on multiple attributes of the user, the resource, and the environment, such as user role, resource sensitivity, time, or location. The example given aligns with each model: the owner grants read access to a file demonstrates DAC; clearance levels governing access to data labeled with classifications demonstrates MAC; and access decisions based on user attributes, resource attributes, and context shows ABAC in action. Other options mix up concepts—for instance, time-based or password-based rules don’t capture the distinct mechanisms of MAC or ABAC, and role-based or generic policy descriptions don’t fully illustrate the attribute- and label-driven distinctions. This combination makes the example a clear illustration of DAC, MAC, and ABAC with concrete details.