What are access control lists (ACLs)?

Access control lists (ACLs) are critical in network security as they consist of rules that determine whether specific traffic is allowed or denied access to different parts of a network. These rules are implemented on routers and firewalls to filter traffic based on defined criteria such as IP addresses, port numbers, or protocols.

By using ACLs, network administrators can control which users or systems can communicate with one another, thereby enhancing security and managing network resources effectively. For example, an ACL might permit HTTP traffic to a web server while blocking all other types of traffic to that server. This selective access is crucial for protecting sensitive data and ensuring that only authorized users can interact with network devices or services.

The other options describe functionalities that do not align with the core purpose of ACLs. Managing user passwords pertains to authentication rather than traffic control. Device inventory management involves keeping track of hardware and software assets, which is unrelated to ACLs. Similarly, protocols for data encryption focus on data confidentiality and integrity, rather than the governance of network traffic flow.