For an Access Control List to take effect, it must be applied to which of the following?

An Access Control List (ACL) is a set of rules that allows or denies traffic based on specified criteria. For an ACL to take effect, it must be applied to an interface on a networking device, such as a router or switch. The reason for this is that interfaces are points where traffic enters or exits a device, allowing the ACL to inspect packets and enforce policies based on the defined rules.

When applied to an interface, ACLs can control both inbound and outbound traffic. By placing the ACL on an interface, it monitors the traffic flowing through that interface and makes decisions on allowing or blocking packets according to the rules specified in the ACL.

While a router, a switch, and a network are involved in traffic management, it is the specific interface that directly controls how traffic is handled based on the ACL. Hence, for the ACL to function correctly, applying it at the interface level is essential.