In short, if browser accepts third-party cookies, tracking cross domains is possible in Marketing Cloud ID.
The link MCID cross-domain tracking will help you to understand the concept.
But if your browser reject third party cookies, FPC is the only option.
Visitor ID service should serve the same MID as long as you are using same Marketing cloud ORG ID in the configuration and the demdex cookie is present.
Safari does not accept third party cookies nowadays I believe so I would say the best solution would be appendVisitorIDsTo (Cross-Domain Tracking) .
Remember that the AMCV_ cookie is set as first party cookie always so using the solution above should work . Only demdex cookie is set as third party cookie.
FPC cookie implementation is also valid as per Bupathi advice but I prefer the solution to append the visitor IDs.
Hi Alexis Cazes Adobe - I tried using appendVisitorIdsTo() but did not have any luck. The correct MCID is not passing through on Safari. I even included it on a specific link such as the example here suggests and had the query parameter present upon page load at the second domain. The MCID was not successfully overwritten with what was in the query parameter.
Any other solutions or idea why this would happen?
I will need some code example to be able to help.
Do you have correct:
VisitorID services version
Is it deployed in the correct order ?
Site 1- fully DTM
Visitor ID- 3.3 (loaded first)
Analytics - 2.11
Site 2- Visitor ID is loaded with DTM
Visitor ID- 2.5 (loaded first)
Analytics - not sure analytics is done server-side
Where is the MCID not overwritten ? The adobe Analytics server call or the cookie itself?
Does the descrination site already has an MID ?