“Hidden Networks” still appears in the Windows network list, so others will still know that there’s a network nearby.
Even if you disable SSID broadcasting, the SSID will nonetheless still be included—unencrypted—in some Wi-Fi traffic, where it can certainly be intercepted by eavesdroppers. The SSID is included in the association process, for example, so when a device connects or reconnects to the network, an eavesdropper could capture the SSID at that point. While Windows and most other devices natively won’t pick up on the SSID in this other traffic, it is captured by many third-party Wi-Fi analyzers, such as Kismet, CommView for WiFi, and Airmagnet.
Since the SSID can be so easily intercepted by eavesdroppers, I would never recommend disabling its broadcast in place of encryption. Disabling it after enabling WPA2 with a strong password might deter the most casual of hackers from attacking your network, but that can have a negative impact on a large network’s performance because it increases the amount of background traffic traveling over the network.
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