Before a single tray slides in, the rack has to be level, anchored, grounded, and powered. Rushed prep here cascades into every later problem — misaligned blind-mate connectors, grounding faults, strained cabling. Get the foundation right.
Rack prep is the foundation the whole deployment stands on — literally. A rack that isn't level makes blind-mate connectors misalign; one that isn't properly grounded is a safety hazard in a high-current DC environment; power infrastructure mounted wrong risks the entire rack. Ten percent of the exam, but 100% of what everything after it depends on.
This domain covers the physical readiness of the rack itself: receiving and inspecting it, positioning and leveling, anchoring (including seismic where required), grounding and bonding, mounting the power infrastructure (power shelves and DC busbar), and staging rails and manifolds so the compute and switch trays can go in cleanly.
Order matters. Each step assumes the previous one is done correctly.
Leveling isn't cosmetic. If the rack isn't level and square, blind-mate power and data connectors won't seat properly when trays are inserted — you'll chase intermittent faults that trace back to a rack that was a few millimetres out. Level before you mount anything.
In a rack pushing high-current DC through a busbar, grounding and bonding are the difference between a safe install and a hazard. They're distinct ideas:
| Term | What it means | Purpose |
|---|---|---|
| Grounding | Connecting the system to earth | Provides a safe path for fault current; stabilizes voltage reference |
| Bonding | Electrically joining all metal parts together | Ensures every conductive surface is at the same potential — no dangerous voltage between parts |
Practically: bond the rack frame, rails, doors, and mounted equipment to a common bonding point, and connect that to the facility ground per the design. Use proper conductors, listed lugs, and correct torque — a loose or corroded ground connection can be worse than none because it looks connected.
Ground = to earth. Bond = to each other. You do both so that no two metal surfaces can ever sit at different potentials and fault current always has a safe path.
With the rack level, anchored, and bonded, mount the components that will energize it.
Rectify facility AC to DC. Mount securely, confirm orientation and input feed type, and verify they match the rack's voltage configuration.
The vertical rail the trays clip onto. Mount to spec, confirm insulation/covers are intact, and keep it de-energized (LOTO) until commissioning.
Install tray rails at the correct U positions per the elevation drawing so trays align with the busbar and manifold drops.
Stage the in-rack cooling manifold and verify quick-disconnect positions line up with each tray drop before any coolant is introduced.
Never treat the busbar as safe because trays aren't installed. Until commissioning, keep power infrastructure under lockout/tagout and covers in place — this is where Domain 3 and Domain 7 (safety) overlap.
The last prep step sets up a clean tray install. Confirm the rack is ready to receive compute and switch trays:
"Level, lock, land, label." Level the rack, lock out the power, land (mount) the power/cooling infrastructure, and label positions — then you're ready for trays.
Rack-prep questions reward knowing the correct sequence and the safety rules behind it. Rehearse with explained answers.
Practice Rack Infrastructure Prep →NCP-ARI-style questions on Domain 3. Choose an answer to see the explanation.
Pick the prep area you want to lock down.
Tap a card to flip it.
For educational use only · Not affiliated with or endorsed by NVIDIA Corporation. Follow the manufacturer's installation documentation and your site's electrical and safety standards for all grounding, bonding, and power work.
