&tt=vast2at the end, since it tells the delivery how it will render the information. Adnuntius supports VAST 2.0, 3.0, 4.0, 4.1 and 4.2. To deliver a VAST 3.0, 4.0, 4,1 or 4.3 ad, you must use either a
&tt=vast4-2parameter instead. The example above is the simplest version of HTTP delivery for ads. More parameters about user and targeting can be added as well.