Which type of frame in WiFi announces SSID to the network?

The correct answer is the beacon frame. In WiFi networks, the beacon frame is specifically designed to announce the presence of a network by broadcasting the SSID (Service Set Identifier). The beacon frame is part of the management frames category, which is used by devices to manage and maintain the connection to the wireless network. The inclusion of the SSID in the beacon frame allows client devices to discover the network and decide if they want to connect.

These beacon frames are periodically transmitted by the access point to inform all nearby devices of the network's availability, presence, and other important parameters such as supported rates and security protocols. This fundamental function aids devices in identifying and associating with the appropriate wireless network.

While other types of frames exist within the WiFi protocol, such as data frames, which carry actual data payloads between devices, and control frames, which are used to control access to the medium, they do not serve the purpose of announcing the SSID. Therefore, understanding the role of beacon frames in network discovery is crucial for grasping how wireless networking operates.