To ensure that service to clients is not interrupted, pause all Web and File Transfer Protocol (FTP) sites on the Web server before taking the server offline. Pausing a site prevents the site from accepting new connections, but does not affect requests that are already being processed. Stopping a site does not interfere with other Internet services that are running.
You can pause a Web or FTP site by using either IIS Manager or a command-line script.
Credentials: Membership in the Administrators group on the local computer.
As a security best practice, log on to your computer using an account that is not in the Administrators group, and then use the Run as command to run IIS Manager ...