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The appliance generates the following rules in the dhcpd configuration file:
 

You can also define more complex rules using the AND and OR logic as follows:

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If the NIOS appliance receives address requests with the user class mobile and there are no available addresses in address range 2 but there are available addresses in ranges 1 and 3, the appliance begins assigning addresses from address range 3 (because its addresses are higher than those in range 1). Then, if all addresses in range 3 are in use, the appliance begins assigning addresses from address range 1. If you want the appliance to assign addresses to mobile users (that is, those identified with the user class mobile) exclusively from address range 2, then you must apply user class filters for "mobile" to address ranges 1 and 3 that deny lease requests matching that user class.

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