A Virtual IP is primarily used to allow multiple devices to act as a single host for the purpose of redundancy and load balancing. In this scenario, if one device fails, the Virtual IP can still be accessed via the remaining active devices, ensuring service continuity. This option encapsulates the primary use of a VIP in high availability configurations, where uninterrupted service is critical. The other answers, while partially reflecting possible uses or aspects of network configurations, do not correctly represent the primary function of a VIP.