If the flow of your website user experience moves between more than one domain (e.g. WHMCS is hosted on whmcs.domain.com and your main website on domain.com), you should set up your Universal Analytics tags to measure those visits as one between your website and WHMCS. Without this functionality, Google Analytics will treat this user as two separate visitors, which will inflate then number of users that appear in your reports. This occurs even if both domains use the same Tag Manager container and Analytics account.
What is cross-domain tracking in Google Analytics?
In the context of Google Analytics, cross-domain tracking is the tracking of website users and their activities across two or more domains. By default, Google Analytics is not able to track website users and their activities across multiple domains. That is because Google Analytics uses first-party cookies which can be read by only that domain which issued it. You would need to manually set up cross-domain tracking.
Why do you need cross-domain tracking in WHMCS?
If the flow of your website user experience moves between more than one domain (e.g. WHMCS is hosted on whmcs.domain.com and your main website on domain.com), you should set up your Universal Analytics tags to measure those visits as one between your website and WHMCS
Without cross-domain tracking set-up, you won’t be able to understand and track a user’s journey which spans across multiple domains. For example, consider the following scenario:
A user landed on your main website besthost.com via the search term ‘best website host’ on Google.
He then navigated to your WHMCS cart page say at whmcs.besthost.com/store/dedicated-servers to make a purchase. As both whmcs shopping cart and the order confirmation page are hosted on whmcs.besthost.com subdomain.
Now without cross-domain tracking set up, Google Analytics will report the same user as two different users: one user visited besthost.com and a different user visited whmcs.besthost.com.
And the user session that actually spans across the two domains will be counted as two different GA sessions instead of a single session. So the GA report of besthost.com may tell you that a user visited besthost.com via the search term ‘best website host’ on google but did not make a purchase or conversion.
The GA report of the website whmcs.besthost.com may tell you that a user visited whmcs.besthost.com/store/dedicated-servers from besthost.com and then made a purchase or conversion.
So without cross-domain tracking setup, your main domain would end up getting all the credit for conversion instead of the search term ‘best website host’ and google organic search traffic.
Consider another scenario:
A user landed on your main website besthost.com via the search term ‘best website host’ on Google. He then navigated to WHMCS cart page at whmcs.besthost.com/store/dedicated-servers.
After completing the purchase, he redirect to main website besthost.com as the order confirmation page is hosted there.
In this case, GA may attribute sales to whmcs.besthost.com instead of the organic search term ‘best website host’.
Thus, without cross-domain tracking setup, you may have a hard time determining the original source of your goal conversion and/or ecommerce transaction. Without a cross-domain tracking setup, most of your conversions could end up being attributed to direct traffic or to a wrong traffic source.
When do you need configure cross-domain tracking for WHMCS?
You need cross-domain tracking when your WHMCS spans in a diferent domain and you want Google Analytics to treat GA sessions spanned across different domains as a single session. If you use the same Google Analytics Propertie across diferent domains and host the products on the same WHMCS you need configure cross-domain ASAP.