If your Express Store and your main website have different domain names, you will need to enable cross-domain tracking. Typically, you won’t need to enable cross-domain tracking, however, here are some examples to help you decide:
Example NOT requiring cross-domain tracking (typical):
- Dealer Website = earlstewarttoyota.com
- Express Store = express.earlstewarttoyota.com
Example requiring cross-domain tracking (less common):
- Dealer Website = paragonhonda.com
- Express Store = express.paragoncars.com
All that matters is the domain (the part closest to and including the .com). In the example above, paragonhonda.com is different from paragoncars.com. This example requires cross domain tracking to be enabled. Earlstewarttoyota.com does not require cross-domain tracking because the domain (earlstewarttoyota.com) is the same for both the Dealer Website and the Express store.
Things to the left of the domain do not matter – Google treats them as the same domain. If you require cross domain tracking, follow the instructions for ‘Set up cross-domain measurement by modifying 'analytics.js’ here.