Prebid.js fans out one HTTP request per bidder 1 — each sees the user’s real IP, cookies, and page URL. Bids race bidderTimeout 2: when it fires, the auction runs with whatever arrived. Winning bid’s targeting keys go to the ad server 3, which picks the creative and renders it 4.
FIELD NOTES
- bidderTimeout is a hard cutoff, but JS event-loop bids can slip in
- Unresolved CMP (consent) cancels the auction, not just delays it
- Unlike server 9, browsers cap ~6 connections per origin