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Probing the neighborhood

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Probing the neighborhood

Let's go a little more into the world of probes and sensors, since they are the foundation of the Discovery feature.

Probes are sent on their errands by the MID Server, and sensors live on the instance. In the census world, the sensor would work out of the census office. The MID Server is out in the network (neighborhood) using probes (census agents) to gather information. That information is returned to the instance where the sensor processes the data. Sometimes, when the MID Server passes the information to the sensor, the sensor decides that it needs more information and makes the MID Server run more probes. For example, if the MID Server tells the sensor the device is running a Web server, then the sensor is going to tell the MID Server to go back to that IP address and run a probe to ask the device what Websites it hosts.

The following diagram demonstrates the conversation between the MID Server and the sensor.
Figure 1. MID Server Probe
Hopefully, you have a basic understanding of Discovery by now. To recap, we'll go over the fundamentals of Discovery, then run through a scenario that uses these fundamentals.
  • Discovery is the process of extracting information out of devices and recording it in a uniform way.
  • The Discovery process uses your ServiceNow instance and one or more MID Servers.
  • The MID Server is a light-weight (small and simple) agent that runs on a server in your network.
  • The MID Server needs ranges of IP Addresses and credentials (user names and passwords) before it can begin discovering.
  • The MID Server gathers information (using probes) and passes it to the instance to be processed (using sensors).
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