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18_1587202115_ch16.qxp 9/29/08 2:42 PM Page 300300 CCNA Wireless Official Exam Certification GuideFigure 16-3 Wireless Networks DetectedWhen you click the link, a new window appears, allowing you to connect one of the avail-able networks, as shown in Figure 16-4.You can select one of the available networks and click the Connect button. If there areany security settings, you are prompted for that information. You will probably find theprofile setup in Windows to be very easy, especially because it detects networks for you.You might also wonder how this process works. The next section covers the process inmore detail.How the WZC Tool WorksWhen a Windows-based computer boots up, the Wireless Zero Configuration reports anynetwork that is being broadcast, usually via a balloon window at the bottom right of thescreen. This is because when a WZC client attempts to access a network, it uses an activescanning process. This differs from other methods, such as passive scanning, which is usedby other clients.Note: The concept of passive scanning simply involves the client’s waiting until it hears abeacon from an access point.With active scanning, the WZC sends probe requests with a blank SSID field. This iscalled active null scanning. This type of scan causes access points (AP) that are in rangeto respond with a list of available service set identifiers (SSID). If one of the receivedSSIDs exists on the preferred networks list in the WZC, the WZC connects to it, or atleast tries to. If that connection fails, the WZC tries the next SSID from the preferred net-works list that was seen to be available from the scan.If none of the SSIDs that were learned from the active null scan or in the preferred net-works list result in a successful connection, the WZC looks for any ad hoc network in theavailable networks list. If the WZC finds an ad hoc network, it connects to it, which couldbe a security issue. This happens in the background without any user intervention. Whenyou set up the profile, you can select an option to connect to only infrastructure net-works.If the connection attempts are still unsuccessful at this point (and assuming that you areallowing ad hoc connections), the WZC makes itself the first node and thus allows others