What causes impression count discrepancies between DSP and SSP?
Answer
Different counting points. If the DSP counts wins (nurl fired) while the publisher side counts rendered or billable impressions (burl, which the spec ties to the billing event), every won-but-never-rendered impression becomes a discrepancy. Add timeout losses after win, creative wrappers that fail to load, and timezone boundaries on reporting, and 5 to 10 percent gaps are common. The spec's answer is burl: bill on the billing notice, not the win notice. When reconciling, first agree on which URL each side counts and in which timezone the day is cut.
Go deeper
More questions on debugging, no-bids, and validation
- Why is my bidder not receiving bid requests? Work the path from the exchange inward: confirm the endpoint the exchange has on file matches what you deployed (scheme, host, path), that your endpoint returns a well-formed response or HTTP 204 quickly enough to stay under the exchange's timeout, and that traffic filters on the exchange side (geo, media type, QPS caps, pretargeting) are not excluding you.
- Why is my bid rate low even though I receive requests? Start by separating deliberate no-bids from failures.
- How do I find out why my bids are losing auctions? Ask for loss reasons via the loss notice URL.
- How do I debug a systematic OpenRTB no-bid? If the bidder returns a BidResponse with nbr set, the code tells you where to look: nbr 2 is Invalid Request, which means the bidder could not parse or accept your bid request, so run the request through a validator before anything else.
- What does HTTP 204 mean in OpenRTB, and how is it different from nbr? HTTP 204 No Content is the spec's preferred way for a bidder to say it has no bid: no body, cheapest possible round trip.
- How do I validate an OpenRTB bid request? Paste it into a validator that checks against the actual spec catalog, not just JSON syntax.
All 93 questions are listed in the OpenRTB FAQ.