Remote Installation Services
RIS, Remote Installation Services is a Microsoft-supplied server that allows PXE BIOS-enabled computers to remotely execute boot environment variables.
These variables are likely computers that are on a company's (or that company's client's) network. RIS is used to create installation images of operating systems or computer configurations, which can be used to demonstrate the installation process to users whose machines have been granted access to the RIS server. This eliminates the need to use a CD-ROM for installing an operating system.