We recently migrated to the Experience Cloud ID service. One of the drivers behind this was to enable cross-domain tracking, and after reading Data Collection CNAMEs and Cross-Domain Tracking we opted to enable CNAME support.
Background
We own two domains, Domain A (our flagship domain) and Domain B, and are using two Adobe DTM web properties to manage the Experience Cloud ID Service. We want to know how many visitors reach Domain B after seeing Domain A independently, i.e. not through a link on Domain A. For this reason we did not focus on setting up the appendVisitorIDsTo function, since there are limited opportunities to navigate between Domain A and Domain B via a direct link.
- We implemented the Experience Cloud ID service in Adobe DTM using two web properties. Both web properties use the Experience Cloud Organization ID, tracking server, secure tracking server, and library version.
- We did not add anything to the General Settings or Customer Settings fields in the Experience Cloud ID Service Settings section of Adobe DTM.
- Adobe Analytics is managed in Adobe DTM for Domain B, but in another tag manager for Domain A.
Findings
When third-party cookies are enabled we see the same Experience Cloud ID (MID) in Domain A and Domain B, which is the expected outcome. When third-party cookies are disabled we see different MIDs. This is an unexpected outcome based on what we read in Adobe's CNAME documentation.
We looked at Chrome DevTools to see how the AMCV cookies were being set, paying specific attention to what happened when third-party cookies were disabled.
- When Domain A is visited first, an AMCV cookie appears with Domain A as the domain.
- When Domain B is visited after Domain A, two AMCV cookies appear: one on Domain A and one on Domain B. Both have the same Name. These cookies have different MIDs.
- When examining Domain B's cookies, the cookie set on Domain A has the MID value we would expect to see (i.e. the same as when we visited Domain A), but the MID that appears in the Adobe debugger for Domain B is the value from the AMCV cookie set on Domain B.
Questions
- Did we misinterpret how using the CNAME would allow cross-domain tracking according to Data Collection CNAMEs and Cross-Domain Tracking ?
- Should we add configurations to the General Settings and Customer Settings fields in the Experience Cloud ID Service Settings section of Adobe DTM (Experience Cloud ID Service Settings for DTM )?
- Are we missing other key settings that would allow cross-domain tracking to work properly?
- Should we remove the getInstance() function from the AppMeasurement library used for Domain A, which is not managed in Adobe DTM? This was mentioned on Experience Cloud ID Service.
- Could a timing delay in when Adobe scripts run on Domain B cause an issue? We seen that the Experience Cloud ID service fires much faster on Domain A.