Round robin

http://www.computerhope.com/jargon/r/rounrobi.htm

Round robin

Round robin is a method of distributing multiple sources to one of the many devices or connections. For example, a company may have multiple servers that are identical to each other. When the first user attempts to access information from the server they may be referred to "SERVER_1"; however, the next user is directed to "SERVER_2" regardless of its load.