To communicate with other NetScaler Gateway appliances, each appliance requires knowledge of the other appliances, including how to authenticate on NetScaler Gateway. RPC nodes are internal system entities used for system-to-system communication of configuration and session information. One RPC node exists on each NetScaler Gateway and stores information, such as the IP addresses of the other NetScaler Gateway appliance and the passwords used for authentication. The NetScaler Gateway that makes contact with another NetScaler Gateway checks the password within the RPC node.