TCP monitoring check

How does the TCP Monitoring work?

The TCP monitoring check is a part of the ClouDNS motoring service, that makes a TCP connection to the given IP address on the chosen port number. If the connection is unsuccessful, the check is marked as DOWN.

TCP is used to provide a reliable, ordered data delivery between two applications. It is a delivery service that guarantees that all bytes received will be identical and in the same order as those sent.

Discover TCP Monitoring service by ClouDNS and get started now!

Why do you need to start using it?

TCP is important because it establishes the rules and standard procedures for the way information is communicated over the internet. It is the foundation for the internet as it currently exists and ensures that data transmission is carried out equally. By enabling TCP Monitoring you are checking that a service is accessible on a given port on the network device by establishing a connection before data transmission begins. So, we can say that TCP monitoring is important for:

  • Identifying and diagnosing network problems
  • Monitoring traffic patterns
  • Optimizing performance


Each Monitoring check provides a debugging option which you can use to find out where the problem comes from using Traceroute information - The traceroute command is used to determine the path between two connections. Often a connection to another device will have to go through multiple routers. The option can be found in the Monitoring check settings page on the right side of the "Uptime changes section".

Which port to use for TCP monitoring check?

The Transmission Control Protocol typically utilizes two ports for monitoring, the source port and the destination port. The source port is the port on the local device used to hold outgoing traffic, while the destination port is the port on the remote device used to receive incoming traffic.

TCP is responsible for ensuring that data is transferred reliably and correctly between two nodes, such as a web browser and a web server. To do this, it uses port numbers, which are like electronic “doors” that allow data to come in and out. For most web applications, TCP port 80 is the standard. This port is used to transfer Hypertext Transfer Protocol (HTTP) data, allowing users to access webpages. 

Aside from port 80, other ports used for TCP are:

  • Port 22: Secure Shell (SSH) access to Linux
  • Port 25: Simple Mail Transfer Protocol (SMTP) access for email
  • Port 53: DNS lookup via TCP
  • Port 161: Inbound SNMP GET requests
  • Port 162: Outbound SNMP TRAPS
  • Port 443: Hypertext Transfer Protocol Secure (HTTPS) default port for secure browser and web services interfaces
  • Port 7102: Alternate port for secure browser and web services interfaces 
  • Port 7104: Alternate port for browser access
  • Port 7105: Alternate port for secure browser GUI access

Note that there are other ports used to monitor TCP that you can use. It depends on the specific use case.


Question: Can I use TCP monitoring to detect security threats?

Answer: Yes, you can use it to detect malicious activity and potential security threats, such as a Man-in-the-Middle attack.

Question: How frequently should I check my TCP connections?

Answer: It is recommended that you check your TCP connections at least once a day. If your network is critical or has a high volume of traffic, it is recommended to check it multiple times a day. We provide monitoring intervals of 1, 5, 10, 15, 20, 30, and 60 minutes.

Question: In which plans can I take advantage of the TCP monitoring check?

Answer: You can benefit from TCP monitoring check in any of our Monitoring service plans. In addition, with Premium DNS, DDoS Protected DNS and GeoDNS plans, you can take advantage of 1 monitoring check.

Question: Can I monitor multiple networks at once with ClouDNS TCP monitoring?

Answer: Yes, in our Monitoring service plans S, M and L, you can benefit from more than 1 monitoring check.

Suggested Monitoring check types

Last modified: 2023-10-30
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