What is the traceroute command used for and what does it show?

The traceroute command is a basic tool that is used to monitor network status. traceroute is used on Linux systems to display the route from your server through nodes to the destination (domain or IP), and also displays a delay. This command is used when you need to find out about the route and about all the jumps that the package performs. And if a problem arises on one of the nodes, you can determine which one.

Before you begin, you need to make sure that traceroute is installed on the server, if not, you can do this through the package manager of your Linux distribution. Using the command is very easy, just in the console after the utility we specify the host address, it can be a domain or IP.

Let us briefly analyze the traceroute command implementation algorithm itself. traceroute uses a set of TCP / IP protocols, for sending it sends test UDP packets with a short lifetime, and then tries to call ICMP response “TIME_EXCEEDED” from each gateway along the path to the specified host.

A packet is sent from its source to its destination via a router. Each line contains and displays the details of interaction with each router encountered on the screen. Where the header contains the lifetime (TTL) field, which is a conversion count counter. And the first column is responsible for this parameter in the screenshot, it contains sequential numbering of jumps. When executed, traceroute increments TTL by 1 and attempts to send packets again. This process is repeated until the destination specified in the command is reached or the maximum number of jumps is checked (there are 30 by default). When the packet reaches its maximum TTL value, the last jump in the line will send the ICMP TTL Exceeded packet back to the source. This answer is what traceroute is looking for. The ICMP TTL Exceeded message contains important information, such as the time it takes to reach this transition, and the name of the router or its IP that makes this response.

The traceroute command is basic and is used in routine administration to understand network problems.