Architecture: PRTG Core Server, PRTG Probe and the User Interfaces

PRTG Network Monitor consists of different parts which can be divided into three main categories.


System parts:

  • PRTG Core Server: This is the central part of a PRTG installation and includes data storage, web server, report engine, a notification system and more. See below in this section.
  • PRTG Probe: The part of PRTG on which the actual monitoring is performed. See below in this section.

Note: Core server and probe(s) are running as Windows services which are permanently run by the Windows system without the requirement for a logged-in user.

Control Interfaces:

  • PRTG Web Interface: The AJAX-based web interface is used for configuration of devices and sensors, as well as the review of monitoring results. See section Web Interface.
  • PRTG Windows GUI: A native Windows application as web interface alternative. Supports the most important features. See section Windows GUI.
  • PRTG iPhone interfaces: Monitor your network on the go with the iPhone App for PRTG Network Monitor or the iPhone web interface. See section iPhone Interfaces.

Basic system administration interfaces:

  • PRTG Core Administrator: Used to configure very basic PRTG Core Server settings, such as administrator login, web server IPs and port, probe connection settings, system language, and more. See section PRTG Server Administrator at the description of system settings and administration.
  • PRTG Probe Administrator: Used to configure very basic settings such as name of the probe, IP and server connection settings, and more. See section PRTG Probe Administrator at the description of system settings and administration.

PRTG Core Server

The Core Server is the heart of your PRTG system and performs the following processes:

  • Configuration management for object monitoring.
  • Management and configuration of the connected probes.
  • Database for monitoring results.
  • Notification management including a mail server for email delivery.
  • Report generator and scheduler.
  • User account management.
  • Data purging (culling data that is older than 365 days, for example).
  • Web server and API server.

The built-in, fast and secure web server (no IIS or Apache is required) supports HTTP as well as secure HTTPS (via SSL). It serves the web interface when accessed with a browser and also answers PRTG API calls (e.g. for the Windows GUI).

PRTG Probes

On a "probe", the sensors for a device perform the actual monitoring. The probe receives its configuration from the Core Server, runs the monitoring processes and delivers monitoring results back to the Core Server. A Core Server always has a local probe running on the same server. Additionally a Core Server can manage an unlimited number of remote probes in order to achieve multiple location monitoring.

The actual monitoring is performed by PRTG Probe processes which run on one or more computers. During installation the so-called "local probe" is automatically created by the system. In a single-probe installation - which is the default setup - all monitoring is performed by the local probe. Additional so-called "remote probes" must be created by the user. They are using SSL secured connections to the core and allow to securely monitor services and systems inside remote networks which are not openly accessible or secured by firewalls. The following chart shows an example:


The PRTG Core Server inside the corporate LAN (bottom right) is able to monitor services and servers in remote offices, data centers and behind firewalls using remote probes. See Multiple Probes and Remote Probes for more information on remote probes.

After receiving their configuration from the core system, all probes are able to work independently of the core server for some time, e.g. in case the connection between probe and core is lost due to connectivity problems. During a connection loss a buffer stores a maximum of 500,000 sensor results in RAM memory of the remote probe system (up to 50 - 200 MB). This means that for 100 sensors with one minute interval the monitoring results of up to 3 days can be buffered (or 52 minutes for 10,000 sensors with one minute interval). The probe automatically reconnects to the core as soon as it is available again and transmits all monitoring results gathered during the connection loss.

PRTG automatically monitors the "system health" of the core server and each probe in order to discover overloading situations that may distort monitoring results. To monitor the system status of the probe computer, PRTG automatically creates a few sensors for all installed network cards. These include a "Probe Health", a "Disk Free" sensor, and a sensor to monitor the bandwidth:


It is recommended to keep these sensors, but you can optionally remove all except for the "Probe Health" sensor. It measures various internal system parameters of the probe system hardware and the probe's internal processes and then computes a resulting value. Frequent or repeated values below 100 % should be investigated, please check the sensor's channels for details.


Keywords: Probe,Local Probe,Core Server,Architecture,Remote Probe