What is Host in Computer?
Host in computers refers to the main computer which serves as the main control of the network. Other computers and devices are connected to such a computer.
A peripheral is a device attached to a host computer, but not part of it, and is more or less dependent on the host. It expands the host's capabilities, but does not form part of the core computer architecture. But a Computer is plugged into the UPS not vice versa. Its not dependent on the host. Power is not the host capabality so UPS doesnot expands it. So UPS is not a peripheral device.