What is a backplane/midplane?

• A. PCIe card used for network expansion.
• B. A software layer for BIOS configuration.
• C. PCB interconnect that links hot-swap drive bays or blade modules to the motherboard and power.
• D. A removable battery pack for memory.

Answer: (C)

A backplane or midplane is the main PCB interconnect inside a server chassis that ties the system’s motherboard (or blade modules) to the drives and power it needs. It sits in the enclosure and provides the electrical pathways and standardized connectors that deliver power and data signals to hot‑swap drive bays or blade modules without running individual cables from every component to the motherboard.

In practice, the backplane handles power delivery to each drive or blade and routes data signals (such as PCIe, SATA, or SAS) between the modules and the system bus. This design enables components to be inserted or removed while the system is running (hot-swapping) and keeps cabling tidy and reliable. A midplane is a closely related concept used in some designs, providing a fixed signaling plane between modules to reduce cable clutter and improve signal integrity.

So the description that matches this role is the PCB interconnect that links hot-swap drive bays or blade modules to the motherboard and power. The other options describe different things (a PCIe expansion card, a software BIOS layer, or a removable memory battery pack) that aren’t this interconnect function.