Which of the following technologies is specifically categorized under Web servers?

The technology that is specifically categorized under web servers is Apache HTTP. Apache HTTP Server, commonly referred to as Apache, is one of the most widely used web server software applications. It is designed to host and serve web content using the HTTP protocol, making it an essential component in the web server category. Apache is known for its ability to handle multiple requests simultaneously and can serve static and dynamic content, making it a staple for many web applications.

Other technologies listed, while related to web development, fall into different categories. Node.js, for instance, is a JavaScript runtime that allows developers to write server-side code, but it is not categorized strictly as a web server. Ruby on Rails is a web application framework for developing database-backed web applications using the Ruby programming language, which tends to focus on application development rather than being a web server itself. JavaScript is a programming language that enables interactive web pages and is primarily executed in the browser rather than functioning as a web server.

Overall, Apache HTTP stands out as the correct answer due to its direct functionality as a web server, whereas the others serve different roles in the technology stack.