What does a standard ACL primarily control in a network?

A standard Access Control List (ACL) primarily focuses on regulating traffic based on source IP addresses. It simplifies the filtering process by allowing or denying packets based solely on the address from which they originate. This means that when a router examines incoming packets, it checks the source IP against the conditions specified in the ACL to determine whether to permit or deny that traffic.

This functionality is essential for controlling access to network resources. By using a standard ACL, network administrators can control which devices or networks can communicate with others, thus enhancing security by limiting access to only authorized sources. This can be particularly useful in segmenting network traffic or protecting sensitive areas of the network from unwanted access.

While other types of ACLs exist, such as extended ACLs which can filter packets based on destination IP addresses, port numbers, and protocols, a standard ACL's primary function is rooted in handling source IP addresses. This focus delineates its role within broader network security measures.