# Connect Reverse ETL Source to The Trade Desk Audience

This guide takes you through the steps to connect a Reverse ETL source to the The Trade Desk Audience destination. Once set up, you can sync your first-party data from the warehouse to The Trade Desk data segments.

## Set up the connection 

{{< warning >}}
**The Reverse ETL feature supports only source-driven pipeline configuration.**

Make sure you have [set up a Reverse ETL source]({{< ref "sources/reverse-etl/_index.md" >}}) and connected it to your The Trade Desk Audience destination before following the below steps.
{{< /warning >}}

1. [Confirm the connection settings]({{< ref "destinations/reverse-etl-destinations/trade-desk-audience/setup-guide.md#connection-settings" >}}) for The Trade Desk Audience destination and click **Continue**.

2. In the **Where do you want to sync data to?** section:

    - Select **Create New audience** if you want to create a new data segment in The Trade Desk Audience. Specify the name and description of the data segment in the respective fields.

    {{< image src="images/event-stream-destinations/fb-custom-audience-new.webp" >}}

    - Select **Use Existing Audience** if you have an existing data segment in The Trade Desk Audience and specify the segment name under **Audience ID**.

    {{< image src="images/event-stream-destinations/fb-custom-audience-existing.webp" >}}

3. Set the [Sync mode]({{< ref "data-pipelines/reverse-etl/developer-guides/sync-modes.md" >}}) to specify how RudderStack should sync the data to The Trade Desk Audiences.
4. In **Choose identifier**, specify the warehouse column that RudderStack uses to identify your records.

{{< image src="images/event-stream-destinations/trade-desk-1.webp" >}}

5. Map your warehouse columns to specific The Trade Desk Audience fields using the **Map fields** setting and click **Continue**.

{{< image src="images/event-stream-destinations/trade-desk-2.webp" >}}

If you have selected **Create New audience** option in Step 2, the new audience will be created in the destination with the same **Audience ID** as in the **Schema** tab of the Reverse ETL connection.

{{< image src="images/retl-sources/audience-id.webp" >}}

## FAQ

#### Why can't I add a Reverse ETL source from the destination page?

The Reverse ETL feature supports only source-driven pipeline configuration. It means that you must configure a Reverse ETL source in RudderStack and then connect it to a new or existing destination. Note that this destination should not be connected to any other source.

See [Reverse ETL FAQ]({{< ref "data-pipelines/reverse-etl/developer-guides/faq.md" >}}) for more information.