Which of the following allows several websites from different companies to be housed on the...

Shared resources is the concept that allows several websites from different companies to be housed on the same virtual server. A virtual server is a software-based server that runs on a physical server and can host multiple virtual machines (VMs). Each VM can run a different operating system and application, such as a website, and have its own allocated resources, such as CPU, memory, disk space, and network bandwidth. However, the VMs share the underlying hardware resources of the physical server, which reduces the cost and complexity of maintaining separate servers for each website. This also enables rapid scalability, as new VMs can be created or deleted as needed.

One of the methods to host multiple websites on the same virtual server is to use virtual hosts. Virtual hosts are a feature of web servers, such as Apache, that allow the web server to serve different websites based on the domain name or IP address requested by the client. For example, a web server can host two websites, a.example.com and b.example.com, on the same virtual server and the same port (such as 80 or 443), by using virtual hosts to map each domain name to a different document root directory. The web server will then deliver the content of the corresponding website to the client based on the domain name in the HTTP request header.