When a S2S real-time outbound transfer occurs, the payload must include the DataPartner_UUID so that the destination platform is able to find the corresponding user and apply any segment IDs to their profile.
How and where does Audience manager collect the DataPartner_UUID in the first place? My theory was that it's passed in one of the demdex requests when a user arrives on site, so that the partner ID and AAM_UUID can be synced, but I haven't been able to find an example of that happening. The other theory is that the partner ID is expected to already be set as a cookie on the client domain, and the name of that cookie is known by the AAM destination, and its value is automatically captured from the incoming analytics request (Assuming SSF is enabled)
Hoping someone can shed some light on this for me!
When a visitor visits the website for the first time where AAM is implemented. AAM assigns it a device ID called demdex ID.
AAM has out of the box integration with most of the famous ad platforms, ad servers, DSPs, data providers etc.
So, when a visitor comes on the website for the first time, AAM initiates a partner ID sync call, and the partner ID is assigned to that device. AAM will assign demdex ID as 1234, but an ad server may identify the same device with it's own ID: ABCD.
So, AAM syncs its own ID with that of partner, and maintains a match table. This process is automated, it does not require any set up or implementation change.
When you activate segments to destination, AAM sends partner IDs to that ad server. That's why you see different segment addressable audience for different destinations.
In order to check this ID sync process, you can open any website in a new incognito window of chrome and look at the network requests, filter it by ibs: and you will see partner ID sync calls.