Google ad server is called Google Ad Manager. Google Ad Manager is the ad server by which Google allows publishers to utilize multiple ad networks like Ad Exchange, AdSense, and various other third-party networks.
Google rebranded its publishers and advertising platforms including DoubleClick, Ad Exchange, AdWords, and many other tools. All of these tools were merged into one platform called Google Ad Manager. Now, Google Ad Manager serves as the flagship ad server from Google, empowering publishers to access AdSense, Ad Exchange, and other Ad networks like AOL, Gemini, Meredith, AdCash, and more.
Read More About What is google adx