1. A network device comprising: one or more processors; a storage device coupled to the one or more processors and configured to store a first policy and a second policy; policy evaluating logic coupled to the one or more processors, the policy evaluating logic configured to receive aggregated information that describes a first set of packets that was processed by the network device, and evaluate the first policy based at least in part on a first item of the aggregated information; a probe controller coupled to the one or more processors and configured to, at least partially in response to the policy evaluating logic evaluating the first policy based at least in part on the first item of the aggregated information, automatically activate a first probe that is configured to generate one or more test packets and that emulates a first set of one or more applications, services, or devices; monitoring logic monitoring performance of one or more second applications, services, or devices based on information about the one or more test packets; wherein the policy evaluating logic is configured to receive a second item of second aggregated information that describes a second set of packets that were processed by the network device, and evaluate the second policy based at least in part on the second item of second aggregated information; wherein the probe controller is configured to, at least partially in response to evaluating the second policy, deactivate a second probe that generated test packets for a second set of one or more applications, services, or devices.