PRTG Manual: Auto-Discovery
The auto-discovery automatically creates a set of sensors for all of the devices that are in your network. The auto-discovery is primarily intended for devices that are in the same network as your probes.
Unless you skip the auto-discovery during the installation process, PRTG runs an initial auto-discovery as soon as you finish the installation of PRTG. It automatically shows you the devices that are available in your network as well as suitable sensors for monitoring.
The auto-discovery has three steps:
1.Scan a network segment for devices via ping (at the group level only).
2.Assess the device type for all of the devices that it discovered in step 1 (via the Simple Network Management Protocol (SNMP), Windows Management Instrumentation (WMI), and other protocols).
3.Create sensor sets that match the discovered device types from step 2. It does this based on built-in device templates that have recommended sensors for many device types. Optionally, it can also create sensor sets via device templates that users created.
You can use auto-discovery groups to use the auto-discovery for a range of IP addresses or for individual devices that you manually created. You can run the auto-discovery one time, on demand via the context menu, or via schedule at every hour, day, or week. If you run the auto-discovery at group level daily or weekly, it automatically creates new devices when they connect to the network and it adds suitable sensors.
PRTG creates a notifying ticket when it discovers at least one new device or sensor. You also receive a ticket if an error occurs. By default, PRTG also sends tickets via email. You can change this in the My Account settings.
HTTP sensors' names indicate the protocol that they use to access the target device (HTTP, HTTP (8080), and HTTPS). This distinguishes HTTP sensors from each other if the auto-discovery adds more than one HTTP sensor to a device.
Note the following restrictions of the auto-discovery:
▪PRTG cannot discover devices that are not reachable via ping. This is because step 1 scans for devices via ping. If, for example, a firewall blocks echo requests, PRTG cannot discover a device behind the firewall.
▪If a device has more than one IP address, it may show up more than once in the auto-discovery results, even though PRTG tries to identify these situations.
▪Auto-discovery on group level does not create new sensors on devices that already exist, but only on newly discovered devices. If you want to automatically add sensors to a device, run the auto-discovery on the device via its context menu.
▪Frequent auto-discoveries of large network segments can lead to performance issues. Because of this we recommend that you only schedule regular auto-discoveries where necessary.
For more information, see the Knowledge Base: Why can automatic auto-discoveries evoke performance issues?
▪PRTG automatically adds suitable device icons to discovered devices. PRTG uses a device's MAC address for this purpose, which it determines via the Address Resolution Protocol (ARP). This only works via IPv4 and not via IPv6. Usually, ARP works only in the local network unless your router supports ARP and you configure it accordingly.
▪The auto-discovery does not apply the user group setting Allowed Sensors. Therefore, the auto-discovery adds all sensors that are defined in the used device templates.
You can run an auto-discovery at any time on a specific device. To do so, right-click the device and select Auto-Discovery | Run Auto-Discovery from the context menu. PRTG immediately starts to search for new sensors to add to the device. If you use the auto-discovery for an auto-discovery group (not available on hosted probes), PRTG adds devices with suitable sensors, if it finds any. If you use it for a device, PRTG adds new sensors, if found. In the corresponding page header bar, you can always see when PRTG ran the last auto-discovery on a selected group or device.
The auto-discovery also adds manually deleted devices or sensors again. If you do not want this to happen, you must always create objects manually.
While the auto-discovery is in progress, you might experience a lower system performance than usual, because PRTG is working in the background to discover your network. Depending on the IP address ranges defined (up to 65,536 addresses), the discovery might run for up to several days before it is complete. You can review the status of the discovery process as follows:
▪In the device tree, next to the group or device name, you can see a percentage value that shows the progress of the auto-discovery.
▪During the auto-discovery, the PRTG web interface displays a box in the lower-right corner that shows the number of active auto-discovery tasks.
▪To stop an auto-discovery, right-click the group or device, and select Pause | For 5 Minutes from the context menu. PRTG pauses monitoring for 5 minutes and stops the auto-discovery tasks.
To disable the initial auto-discovery for a fresh PRTG installation, run the installer in a command prompt and add /NoInitialAutoDisco=1 as parameter. This may be useful for performance reasons or if you prefer to manually add devices and sensors to your installation.
Why can automatic auto-discoveries evoke performance issues?
How can I turn off auto-discovery?
How does auto-discovery with SNMP Traffic sensors work?