After a client discovers a supportable wireless network, what is the correct sequence of operations that the client will take to join it?
When a wireless client wants to join a wireless network, it performs a sequence of operations to establish a connection with the network. The correct sequence of these operations depends on the type of authentication and security mechanism used by the wireless network. In general, the sequence involves three steps: scanning, association, and authentication.
Scanning: The first step is scanning, where the client scans for available wireless networks in the vicinity. The client sends a probe request to discover the available networks. The access point (AP) responds to the probe request with a probe response frame that contains information about the network, such as the service set identifier (SSID), channel, and supported security mechanisms.
Association: The next step is association, where the client selects a network to join and initiates the association process with the access point. During the association process, the client and the access point negotiate the parameters of the wireless connection, such as the data rate, channel, and security mechanism. The client sends an association request frame to the access point, which contains the client's identity and capabilities. If the access point accepts the association request, it sends an association response frame to the client.
Authentication: The final step is authentication, where the client and the access point authenticate each other to establish a secure connection. The authentication mechanism depends on the security protocol used by the wireless network. In general, there are two types of authentication mechanisms: open system authentication and shared key authentication.
Open System Authentication: In open system authentication, the client sends an authentication request frame to the access point, which responds with an authentication response frame. This process does not involve any authentication mechanism and is essentially an acknowledgment of the association.
Shared Key Authentication: In shared key authentication, the client and the access point use a pre-shared key to authenticate each other. The client sends an authentication request frame that contains a challenge text, and the access point responds with an authentication response frame that contains the encrypted challenge text. If the client can decrypt the challenge text correctly, it sends an authentication frame to the access point, which completes the authentication process.
A. Association, then authentication: This answer option is correct for open system authentication. After the client associates with the access point, the client is considered authenticated and can access the network.
B. Authentication, then association: This answer option is correct for shared key authentication. The client must authenticate itself before it can associate with the access point.
C. Probe request, then association: This answer option is incorrect. The probe request is part of the scanning process, and it precedes the association process.
D. Authentication, then authorization: This answer option is incorrect. Authorization is a separate process that occurs after authentication, where the access point grants or denies access to specific resources based on the client's credentials.