Load limits
A web server (program) has defined load limits, because it can handle only a limited number of concurrent client connections (usually between 2 and 80,000, by default between 500 and 1,000) per IP adress (and TCP port) and it can serve only a certain maximum number of requests per second depending on:
- its own settings;
- the HTTP request type;
- content origin (static or dynamic);
- the fact that the served content is or is not cached;
- the hardware and soft limitations of the OS where it is working;
When a web server is near to or over its limits, it becomes unresponsive.