Savvy clients now carry out multiple test campaigns to identify appropriate targeting within a network to achieve maximum performance. But in fact, even for clients running a single campaign, testing is going on constantly within the ad network model. By virtue of having thousands of sites to choose from, a network's technology automatically identifies what sites should continue to show a campaign's creative to achieve the highest ROI. Thus, a network's optimization technology itself is a form of campaign testing.

More traditional methods of testing include copy and concept testing prior to the roll-out of a campaign to ensure a message is resonating well with the target audience.

The importance of creative testing also highlights the ability of networks to achieve lift in key brand metrics. Increasingly marketers are turning to ad networks for their extensive reach, transparency and cost-efficiency to deliver measurable brand advertising performance.