said by docrice :

No and no. The only thing "turning off the SSID" does is null the value of the network name field in the 802.11 beacon. Anytime a station associates or re-associates, that value is sent in the clear within the respective 802.11 frames. For this reason, it's not considered a security measure at all, except to superficially reduce confusion in areas where there are a lot of access points announcing themselves and prevent someone from accidentally selecting your network.

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