Before reviewing the Dotcom-Monitor monitoring algorithm, it’s helpful to define two key terms:

  • Monitoring session: A single monitoring check executed from one location.
  • Monitoring cycle: A full round of monitoring sessions across all selected locations.

How Monitoring Works

Under typical conditions, Dotcom-Monitor runs checks in a round-robin fashion — triggering a monitoring session from one location at a time, in sequence, with the configured frequency. This behaviour continues until at least one location reports a different state from the others (e.g., one returns an error while the rest succeed) or other special criteria are met. Then, Dotcom-Monitor runs monitoring sessions from all selected locations.

When Checks Run from All Locations within One Monitoring Cycle

There are special cases when Dotcom-Monitor will run monitoring sessions from all selected locations rather than from one location at a time:

  • Right after creating, editing, or restarting a device.
  • When an error is detected from one (or more) locations.

Simultaneous Checks

The Allow Simultaneous Checks option controls how Dotcom-Monitor runs monitoring sessions when monitoring from all locations in the above mentioned cases.

  • When set to “YES“: All locations run their monitoring sessions simultaneously.
  • When set to “NO“: Locations run their monitoring sessions one after another as soon as possible.

Default behavior:

  • HTTP-based monitoring (ServerView and WebView): Enabled by default
  • Browser-based monitoring (BrowserView and UserView): Disabled and cannot be changed.

Why disabling simultaneous checks matters

Some applications do not allow multiple simultaneous logins with the same user credentials.

Example:

A web application may automatically log out existing sessions when the same user logs in from another location. If Dotcom-Monitor tried to run multiple browser-based sessions at the same time using the same credentials, the sessions would interfere with each other—causing false login failures or unexpected errors.

To prevent this, Dotcom-Monitor runs browser-based (UserView) sessions sequentially, which is why Allow Simultaneous Checks is disabled and cannot be changed for UV devices.

This sequential behavior can also be useful in other scenarios, such as:

  • Applications that update user carts or profiles in real time and may produce inconsistent results when accessed simultaneously.
  • Workflows involving shared test data (e.g., booking systems, inventory checks) where concurrent access could alter the expected state.

Concurrent Monitoring

In addition to the standard algorithm above, Dotcom-Monitor offers an optional Concurrent Monitoring feature. With Concurrent Monitoring enabled, monitoring sessions run from all selected locations in every monitoring cycle at the set frequency, regardless of monitoring results.

Important Notes:

  • This is an add-on feature that requires approval from a Dotcom-Monitor specialist.
  • Activating Concurrent Monitoring doubles the package price. Contact support to request activation.