Most diagrams of a bid path are drawn by someone selling one of the boxes. This one is drawn from our logs: five hops, a hard deadline at each, and a note on what happens when one of them misses.
The five hops
- Video ad call. The feed knows a slot is about to be visible and says so. It does not guess, and it does not wait for the slot to actually land.
- Bid request. One request out of the edge worker, fanned to every eligible bidder at once.
- Auction. Sealed, first-price, resolved at the edge. No client-side wrapper is involved by this point.
- Bid response. Winner and creative reference come back together — the creative is not a second lookup.
- Ad serve. The frame renders from an already-warm CDN object.
The two hops we removed
The original path had seven. We removed a client-side consent relay, which belongs at the edge where the auction now lives, and a separate creative-fetch round trip, which we folded into the bid response.
Together those two were about 60ms of the old median. Neither removal made the auction smarter; both made it quieter, which turned out to matter more.
What happens when a hop misses
Every hop has a deadline rather than a timeout, and the difference is the whole design. A timeout is a request to hurry up. A deadline is the point after which we stop caring about the answer.
A bidder that misses the deadline is not late. It is out of that auction, and it finds out in the response.
Bidders adjusted within a month once the behaviour was predictable. Fill came back; latency did not.
