# Create VAST Config

In the tab “VAST” within the section "Configuration", you can create and manage your VAST configurations. 

To create a new VAST configuration, click on "Add a VAST config" button and enter the configuration name.

Complete the various fields by referring to the OpenRTB 2.5 Imp.Video specs available [here](https://www.iab.com/wp-content/uploads/2016/03/OpenRTB-API-Specification-Version-2-5-FINAL.pdf). Feel free to reach out to <tech@nexx360.io> if you need assistance.

## Callback options

After auctions have run, three scenarios can be adopted:

* **No callback**

Return either a VAST tag resulting from auctions or an empty VAST.

* **VAST callback**

Embed a VAST tag that will be called in case Nexx360 has no ad to serve. We provide macros to ensure GDPR items are transmitted:

| Macros             | Value                                        |
| ------------------ | -------------------------------------------- |
| {GDPR}             | 0 or 1 if GDPR applies                       |
| {GDPR\_CONSENT}    | The GDPR consent string                      |
| {REFERRER\_URL}    | The url of the page where video is displayed |
| {CACHEBUSTER}      | A unique id for the impression               |
| {DESCRIPTION\_URL} | Description URL                              |

An example would be:

`https://securepubads.g.doubleclick.net/gampad/ads?env=vp&gdfp_req=1&output=vast&iu=/1234/video-demo&sz=400x300&unviewed_position_start=1&ciu_szs=728x90,300x250&gdpr={GDPR}&gdpr_consent={GDPR_CONSENT}&url={REFERRER_URL}&cachebuster={CACHEBUSTER}`

* **Google Tag for GAM competition**

Return a Google Tag enriched with Key Value targeting. It enables competition with orders in the adserver (direct, deals, ADX...).

We need to have a classic VAST tag available, example:

`https://pubads.g.doubleclick.net/gampad/ads?iu=/1234/video-demo&description_url=&tfcd=0&npa=0&sz=640x480%7C1920x1080&gdfp_req=1&output=vast&unviewed_position_start=1&env=vp&impl=s&correlator=`

{% hint style="warning" %}
For this option, Nexx360 requires a connection to your Google Ad Manager (GAM) account to push SSPs orders and line items.\
👉🏼 More infos [here](https://developer.nexx360.io/vast-ctv/connect-your-gam-account).
{% endhint %}