Hi Dino,
There are two types of communication happen between wireless Client (PC) and AP.
1) Control Plane messages are used to setup a session between client and AP and contains all the important information related to session. These messages are always broadcast by the AP and client (PC). An attacker can easily hack the session and launch different type of wireless attacks such as deauthorization attack etc. So WAP2 on SSID encrypt all the control plane messages and defend us from session hacking and other attacks which are very easy to launch.
2) Data encryption is to encrypt the actual data send by the user for example a google request from user and it response from the server, when this data is travel over the wireless network.
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