RMON performs a TCP check to assess the availability of a specified port on a server. This process is crucial for ensuring that services relying on TCP (Transmission Control Protocol) are operational and accessible. The check begins by sending a TCP request to the designated port, which is specified by the user in the "Port" field.

Once a response is received, RMON evaluates the status of the port and displays the availability status in a designated box on the Dashboard. If the response cannot be received within a specified timeout period, RMON sends a warning message.

The check can be created for several countries, regions, or agents at once. To do this, select the desired category in the "Place" field and click + next to the countries/regions/agents for which you want to add the check.

Fill in all the necessary fields, including the "Retries" field, which specifies the maximum number of attempts the system will make to reach the service before it is marked as down and a notification is sent. Additionally, you can specify the runbook in the "Runbook" field to provide a reference guide or set of instructions for troubleshooting the service in case it goes down.

RMON also allows users to configure notifications for alerts about any issues related to TCP checks by selecting from various channels, including Telegram, Slack, PagerDuty, and/or Mattermost, when adding a new check.