正解:D
Application visibility and control (AVC) is a solution that leverages multiple technologies to recognize, analyze, and control over 1000 applications, including voice and video, email, file sharing, gaming, peer-to- peer (P2P), and cloud-based applications1. One of the key components of AVC is application recognition, which uses stateful deep packet inspection (DPI) to identify applications within the network traffic flow, using L3 to L7 data2. DPI is a technique that examines the content of packets beyond the header information, and can classify applications based on their signatures, protocols, ports, or other attributes3. DPI enables AVC to monitor and control application performance, bandwidth usage, quality of service, and security policies4. References := 1: Cisco Application Visibility and Control (AVC) - Cisco 2: Cisco Application Visibility and Control User Guide - Technology Overview 3: What is application visibility and control? | Juniper Networks US 4: Application visibility and control - Secure Internet Access Enterprise