TCP/UDP Check Basics

This article will cover the creation and purpose of TCP/UDP checks. This functionality monitors responses on a TCP/UDP port in intervals ranging from 1 to 60 minutes. The following tutorial assumes you are logged into

Table of Contents

Adding Your First TCP Check


To add a new TCP check, click Monitoring > Checks and then Add New. Select TCP Port as your Check Type.

With a TCP check, you will know which servers are responsive and will have a rapid notification if something goes down. Any business may work with contractors from all over the world who require access to sensitive parts of a website or system. A TCP check is an active monitoring system you can use to ensure that access remains constant and open.

This resource is particularly valuable to IT departments that manage web and internal infrastructure, as well as connectivity.

TCP Check: Ensure FTP is Available from Many Countries


This check helps ensure everyone on your team can access internal resources, such as FTP. It utilizes an advanced setting to customize how many servers can go down before you receive an alert.

Required information for the TCP check includes:

  • Check name
  • Domain name or IP address of the server to check
  • TCP port number to check (21 for the example below)
  • Locations of probe servers (A minimum of three Locations is recommended)
  • A customized alert if three probe servers are non-responsive
  • Escalate the issue to IT Support if downtime is longer than 5 minutes



Use the Escalations tab to set time constraints and contact groups for when the problem should be escalated to relevant contacts, such as an internal IT department.




For a detailed breakdown of each Parameter, please visit the Field Explanation support article.

Failed Checks



If a TCP check fails, the error message will include the failure reason, a list of locations that failed to receive a response, and technical details about the downtime.

The TCP check’s connection timeout is 20 seconds, with a total possible threshold of up to 60 seconds once a connection is established.

UDP Check - Ping Available Messaging Platforms

UDP is best suited for monitoring peer-to-peer sharing tools and applications requiring less packet accuracy. This is useful for IT departments to ping a particular VoIP service and ensure a line is always available for executive conferences or weekly team meetings.

Before you begin, you need to format a string or data to send, and a string to expect that your server will understand and that will recognize.


To add a UDP check, click Monitoring > Checks, then Add New. Select UDP as your check type.


A UDP check requires:

  • A domain name or IP address of the server to check
  • Port number
  • String to Send
  • String to Expect

The UDP check will not run without filling out these fields. Many of the Advanced and Escalation options available in TCP checks are available in UDP checks as well. One useful field for monitoring of UDP might be the Maintenance tab.


Maintenance scheduling allows to ignore failed UDP checks for a specified period. Regular updates might pull the system offline and trigger an escalation for a failed UDP check. Executives that use this system would find it inconvenient to receive fail notifications at odd hours of the night or when known maintenance is occurring. Also, be sure that you're monitoring from a minimum of three locations with a Sensitivity set to two or more locations in order to avoid false positives.

Finalizing Your TCP/UDP Check


Before finalizing your check, utilize the Run Test button to verify your settings are returning the expected results. To run a test, select from any of the probe server locations available to your account from the Location dropdown and click Run Test.


Before saving your TCP check, make sure the following fields are complete:

  • Name of the check
  • Defined check interval
  • Contacts that should be notified
  • Locations of probe servers (A minimum of three Locations is recommended)
  • Select TCP or UDP check type
  • Enter the domain or IP address of the server
  • Port number
  • For UDP, enter String to Send and a String to Expect

Once the check has been created, and any proper escalations or maintenance windows set, no further input is necessary. We can edit the check at a later date to add a new server location, change when and how escalation occurs, or any other parameter as needed.

Optional Parameters


Though the following fields are optional, they have some useful properties that may apply to your particular uptime check. Please refer to the Field Explanation support article for a more comprehensive explanation of terms.

  • String to Send (TCP)
  • String to Expect (TCP)
  • Encryption (TCP)

In the UDP example, we looked at the value of a string to expect, to verify connectivity. For TCP, which provides a higher packet accuracy, developers may find these features useful when attempting to test for correct behavior, for example in APIs, or when monitoring sites or infrastructure in other ways.  

Other Commands


In addition to the check itself, you can schedule routine maintenance downtime, or control how long it takes to escalate downtime events.

Please take a moment to familiarize yourself with the Uptime Checks Field Explanation Support Article. We’ve also included a notes section in this Check for any additional information you’d like to save for future reference.

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