ApacheBench (ab) is also provided by Apache and is a command-line tool. It is a lovely tool for command line lovers. This tool is normally installed on most Linux flavors by default. Also, it is installed with Apache, so if you have Apache installed, you will probably have ab installed too.
The basic syntax for an ab command is as follows:
ab –n <Number_Requests> -c <Concurrency> <Address>:<Port><Path>
Let's discuss what each part of the preceding command means:
n: This is the number of requests for test.c: This is concurrency, which is the number of simultaneous requests at a time.Address: This is either the application URL or IP address of the web server.Port: This is the port number at which the application is running.Path: This is the web path of the application that we can use to test. A slash (/) is used for the home page.Now, let's conduct a test using the ab tool by issuing the following command:
ab –n 500 –c 10 packtpub.com/
As the default port for the web server is 80, it is not required to mention it. Note the slash at the end; this is required to place it there because it is the path's part.
After executing the preceding command, we will have an output that looks similar to the following:

We can see some useful information here, including the number of requests per second, which is 490.3; the total time taken for the test, which is 1.020 seconds; the shortest request, which is 20 ms; and the longest request, which is 52 ms.
The server load limit can be found by increasing the number of requests and concurrency level and checking the web server's performance.