Access Control Lists are applied in which areas?

• A. File Systems, firewalls
• B. Routers
• C. DNS servers
• D. Email servers

Answer: (A)

Access Control Lists define who can do what with a resource. In a file system, ACLs attach to files or directories and specify which users or groups have permissions like read, write, or execute, directly controlling access to the resource. In a firewall, ACLs list which network traffic is allowed or denied based on criteria such as source and destination IPs, ports, and protocols, thereby controlling access to networked services. These two areas are the most representative and widely used contexts for ACLs, making them the best match for this question. While ACLs can appear in other systems like routers, DNS, or email servers, the combination of file systems and firewalls is the classic and most straightforward application.