An ACL is essentially a packet filter. An ACL takes effect only after it is applied to a service module.

The statement is correct. An Access Control List (ACL) is a list of rules used to classify and filter packets based on criteria such as source/destination IP address, port number, and protocol type. By definition, it functions as a packet filter. However, simply creating an ACL on a device does not make it active. The ACL must be applied to a specific interface or service module (e.g., in a traffic policy) for the rules to be evaluated against passing traffic.

This is a True/False question, so there is only one alternative (False). The statement would be false if an ACL could take effect without being applied, or if it was not a packet filter, both of which are incorrect according to fundamental networking principles.

1. Huawei HCIA-Datacom V1.0 Training Material, "ACL Principles", Section: Basic ACL. "An ACL is a packet filter that filters packets based on a set of configured matching rules... After an ACL is created, you need to apply it to a service module to make it take effect."

2. Huawei HedEx Documentation for VRP, "ACL Configuration", Feature Description > ACL Overview. "After an ACL is created, you need to apply it to a service module to make it take effect. Otherwise, the ACL does not take effect."