When you create a campaign, use the Inventory tab to control where your impressions can appear.
In the Inventory tab, click Select Inventory. You can then set up the exchanges, domains & apps, and any domain lists you want to use.
By default, your campaign bids on impressions from all exchanges. You can also choose specific exchanges that you want to use by clicking Select exchanges and checking exchanges in the list.
Click Next to move to the Domains & Apps tab.
Domains & Apps
By default, your campaign bids on impressions from all domains and mobile apps. You can also choose specific domains and apps to target Select domains & apps and checking them in the list.
Click the arrow next to the domain or app name to select it on specific exchanges only. For example, the campaign will target yahoo.com, ebay.com, and mail.yahoo.com on any exchange chosen on the Exchanges tab, but it will target dailymail.co.uk only through PubMatic.
Filters help you find the domains and apps you're looking for in this very long list. See Available Inventory for more information.
Click Next to move to the Domain List tab.
If you want to further control your inventory with a domain list (either a whitelist or a blacklist), select it in the Domain List tab. See Domain Lists, Using Whitelists and Blacklists and Domain Lists for Mobile Apps for more details.