Admission control protocols, authentication mechanisms, and _______ are ways communication networks provide admission control.

The provision of admission control in communication networks helps ensure that only authorized users can access network resources, thereby enhancing overall security and efficiency. Access Control Lists (ACLs) play a pivotal role in this aspect. They are implemented on routers and other network devices to define which users or systems are granted or denied access to specific network resources. By specifying rules about which traffic is permitted based on IP addresses, protocols, and ports, ACLs help maintain control over the flow of data into and out of a network, thus directly impacting admission control.

While router configurations can influence network admission control, they are more about the layout and operational settings of the network rather than a direct mechanism for access authorization. Firewalls do support admission control through their ability to block unauthorized access, but they often rely on ACLs to make those decisions. Encryption techniques, while crucial for securing data in transit, do not play a role in determining whether a user or device is allowed to access the network in the first place.

Thus, the use of Access Control Lists is fundamentally aligned with the objectives of admission control, making it the correct choice in this context.