NIOS stands for Network Identity Operating System
NIOS is proprietary software by Infoblox, and it forms the foundation of every Infoblox network services appliance. Infoblox NIOS software contains a security-hardened Linux-based operating system that exposes no extraneous open ports, no general user log-in, no unneeded OS services, and no root access.
NIOS provides all core services and also provides an integrating framework for all other components of the modular Infoblox solution. Specifically, the Infoblox NIOS platform architecture delivers service and application modules (such as DNS and DHCP); provides a Grid module which allows distributed enterprises to link collections of appliances into a unified Infoblox Grid; offers APIs for the extension of capabilities; and contains core technologies that make Infoblox solutions possible.