What is the primary purpose of an ACL (Access Control List) in networking?

The primary purpose of an Access Control List (ACL) in networking is to control incoming and outgoing traffic on a network. ACLs are sets of rules that determine which packets are allowed or denied access based on specified criteria such as IP addresses, protocols, and port numbers. By implementing ACLs, network administrators can enforce security policies and manage traffic flow more effectively, ensuring that authorized communications are permitted while unauthorized access is restricted.

This is essential for maintaining the integrity and confidentiality of network resources, as well as protecting the network from potential threats or unauthorized users. The ability to specify which types of traffic can pass through interfaces on routers and switches allows for better control over how resources are accessed, which can also contribute to overall network performance and security.