PRTG Manual: Object Hierarchy
All objects in a PRTG monitoring configuration are arranged in a treelike hierarchy to create an easy to navigate list and to give the user the possibility to arrange them in groups that monitor similar devices, services, or particular locations. This hierarchical order is also used to define common settings for larger groups of objects, for example, settings of the Root group apply by default to all other objects underneath (see section Inheritance of Settings).
Object Hierarchy in PRTG
The figure shows the object hierarchy in PRTG:
- Root group contains all objects in your setup; all probes are directly under the root node.
- A Probe contains one or several groups.
- A Group contains one or several devices.
- A Device represents a physical or virtual component in your network that is reachable via an IP address. Several sensors are attached to one device.
- A Sensor monitors one single aspect of a device and has at least one channel.
- A Channel tracks one specific data stream and displays it as part of a sensor.
The Root group is the topmost instance in PRTG. It contains all other objects in your setup. Using the inheritance mechanism, we recommend that you adjust the default settings for the Root group. This will make configuration easier later on, because all other objects then inherit these standard settings by default. Thus, you will not have to set up the same configuration for each object anew.
Each group (except the Root group) is part of a Probe. This is the platform where the monitoring takes place. All objects configured below a probe will be monitored via that probe. Every PRTG on premises core server installation automatically installs a Local Probe service, every PRTG in the cloud instance comes with a Cloud Probe.
You can add additional probes and remote probes to your configuration to include remote devices from outside your network into the monitoring (see section Multiple Probes and Remote Probes). In a PRTG on premises cluster, there is an additional Cluster Probe running on all nodes. Devices on the cluster probe are monitored by all nodes of the cluster, so data from a different perspective is available and monitoring for these devices will always continue, even if one of the nodes fails.
On each probe, there are one or more Groups, which serve merely structural purposes. Use groups to arrange similar objects so that they inherit the same settings. To a group, you add devices. You can arrange your devices in different nested groups to reflect the structure of your network.
Find below a sample configuration: A device tree with local probe, several groups, devices and their sensors.
PRTG Device Tree View
You can add Devices that you want to monitor to each probe or group. Each device in your PRTG configuration represents a real hardware or virtual device in your network. These can be, for example:
- Web or file server
- Client computer (Windows, Linux, or Mac OS)
- Router or network switch
- Almost every device in your network that has its own IP address
Sometimes you may want to add the same device in PRTG several times to receive a better overview when using a large number of sensors for very detailed monitoring, or to use different device settings for different groups of sensors. In PRTG you can simply add multiple devices with the same IP address or DNS name. The sensors on all of these PRTG devices will then query the same real hardware device in your network.
PRTG additionally adds a so called Probe Device to the local probe. This is an internal system device. It has access to the computer where the probe is running and monitors its health parameters with several sensors running on it.
To get a better and more detailed picture about your devices, PRTG automatically analyzes the devices that you add and recommends appropriate sensor types on the device overview tab. In the Recommended Sensors table, click the Add These Sensors button in the corresponding table row to create recommended sensor types with one click.
You can turn off the sensor recommendation in System Administration—Monitoring.
On each device you can create a number of Sensors. Every sensor monitors one single aspect of a device. This can be, for example:
- One network service like SMTP, FTP, HTTP, etc.
- One network switch port's traffic
- CPU load of a device
- Memory load of a device
- Traffic on one network card
- One NetFlow device
- System health of a device
- Other content (for example, of databases, mails, HTTP, XML, files, etc.)
For more information, see this video tutorial: What is a sensor?
Every sensor has a number of Channels through which it receives the different data streams. The available channels depend on the type of sensor. One sensor channel can contain, for example:
- Downtime and uptime of a device
- Traffic in of a bandwidth device (for example, a router)
- Traffic out of a bandwidth device (for example, a router)
- Traffic sum of a bandwidth device (for example, a router)
- WWW traffic of a NetFlow device
- Mail traffic of a NetFlow device
- Other traffic of a NetFlow device
- CPU load of a device
- Loading time of a web page
- Download bandwidth of a web page
- Time to first byte of a web page
- Response time of a Ping request to a device
- Response time of a Remote Desktop service
Video Tutorial: What is a sensor?