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For clients that currently available in LANDesk you can use the script "Create Management Gateway Certificate" under Public Scripts and deploy this to your clients. This script will automatically request a certificate from the LANDesk core server.
It is recommended you only target or deploy certificates to mobile devices such as laptop, as most desktop machines are unlikely to be brought off campus and do not require the use of the management gateway.
You can accomplish manually or even write a query only showing laptops (using Computer:System:Has Battery=Yes in LANDesk and target your computers this way.. 
You can also manually request a certificate by launching BrokerConfig.exe under C:\Program Files\LANDesk\LDClient (or C:\Program Files (x86)\LANDesk\LDClient for 64-bit clients). You must use a valid login for the LANDesk Management console (not LANDesk Cloud Services Appliance). Enter your credentials and click "Send" to request a certifcate.
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