If campaigns are trafficked into the publisher ad server, what level of control does the buyer have over decisioning?

When campaigns are trafficked into the publisher ad server, the buyer has no control over the decisioning process. This is primarily because the publisher ad server is responsible for executing and managing ads according to its own set of rules and priorities. The buyer can influence the campaign's setup prior to trafficking—such as setting targeting parameters, budget, and creative assets—but once the campaign is live in the publisher's environment, the decision-making process regarding when and where ads are displayed is dictated by the ad server.

The publisher's ad server makes decisions based on its inventory management, audience data, and other factors unique to that environment, which means the buyer ultimately lacks direct control over how their campaigns are executed once they are in the publisher's system. This situation contrasts with other scenarios, such as using a demand-side platform, where buyers might have more influence over the decisioning and bidding processes.