What is the primary function of an access list (ACL) in networking?

The primary function of an access list (ACL) in networking is to control the flow of packets based on specified criteria. ACLs are used to permit or deny traffic based on defined conditions such as source and destination IP addresses, protocols, and port numbers. By implementing ACLs on routers and switches, network administrators can manage traffic effectively, enhancing security and controlling access to network resources.

For instance, an organization may decide that certain users should not be able to access specific servers or that only certain types of traffic should be allowed to traverse the network. By using ACLs to enforce these rules, the network becomes more secure and efficient.

The other options, while related to networking, do not represent the primary function of an ACL. Prioritizing certain types of traffic typically involves Quality of Service (QoS) configurations, securing user permissions relates to authentication and authorization processes, and configuring routing protocols is separate from the functionality that ACLs provide.