How to check a hardware seller before you buy: serials, parts and what to refuse.

Get the serial numbers before you pay

A serial number is the one thing about a used machine that a seller cannot describe into being. Ask for the serial of every unit in the quote, before payment, and check it with the vendor:

• Dell: the Service Tag. Dell's support site shows the warranty status and expiry date for a tag. A Dell system bought from a third party needs an ownership transfer, filed with the Service Tag and the previous owner's details, before any remaining warranty can be used.
• Lenovo: the machine type and the serial number together. Lenovo support identifies a server by that pair, so ask for both.
• Cisco: the serial number. Cisco's coverage tool takes a serial and shows whether a service contract covers the device.

Check that the serials agree

The serial on the label, the one the device reports about itself and the one in the seller's paperwork should be the same number. When they differ, ask why before you buy: a replaced board, a relabelled part and a paperwork mix-up look the same from the outside.

On our side, serial numbers are recorded for every unit: every unit we ship is powered on and booted on our bench, configuration checked against the spec, completeness and visual inspection, photos, logs and serials recorded. Our Grade A also requires the labels and serial numbers to be legible and not replaced.

Original and compatible are different products

An original part is the vendor's own. A compatible part is made by another manufacturer to work in the vendor's equipment. It is a legitimate product, but it is a different product, and the difference shows when something fails. Cisco's Non-Entitlement Policy lets it withhold warranty or support when a fault is traced to non-Cisco memory, cables or interface components. Dell's optical troubleshooting article for its PowerSwitch line says Dell does not guarantee that third-party or unqualified optics work reliably, or at all.

So the question is not whether a seller offers compatible parts. It is whether the listing says which one you are getting. A compatible part quoted as original is not a cheaper part, it is a hidden one.

Vendor support on secondary-market hardware

Only the vendor can say whether the vendor will support a machine, so ask the vendor rather than the seller. The answer differs by vendor.

Dell ties the remaining warranty to the Service Tag and the ownership transfer described above, and some contract types, such as Return to Depot and Parts Only, are not always transferable outside the region where they were bought.

Cisco's brand protection page says products bought from unauthorised sources are typically not eligible for Cisco support and do not come with a valid software licence, and its warranty listing says its warranties belong to the original owner and are not transferable. Used equipment can be brought back under support through Cisco's hardware inspection and software relicensing programme: Cisco inspects the equipment, charges an inspection fee per chassis, and requires a new software licence. That applies to used Cisco equipment even when it is bought from a Cisco channel partner; only equipment sold through Cisco Refresh comes without inspection. If Cisco's own support is a requirement, budget for the inspection and ask Cisco whether the new licence fee applies to your purchase before comparing prices: Cisco lists exceptions to it, such as transfers within Europe.

If you suspect a Cisco device is counterfeit, Cisco's Brand Protection team offers a free authenticity check. The management licences on Dell, HPE and Lenovo servers have their own rules; what happens to the iDRAC, iLO or XClarity licence covers them.

What to refuse

Any one of these is a reason to stop and ask again, from us or from anyone else:

• Serial numbers only after payment. That is buying first and checking afterwards.
• A part sold as original with nothing to check it against: no serial, no vendor label, no part number the vendor publishes.
• Vendor support promised by the seller. A seller outside the vendor's own channel cannot promise it; check the serial with the vendor.
• "Fully tested" with no list of steps. How a refurbished server is tested shows what a written procedure looks like, ours included.
• A warranty with no written terms. Ours are on the warranty page.