If you are using a unified version of the tracking code that analytics.js, this has been enabled by default tracking across sub-domains, the tracking code can be used directly, shown in Figure 3-41, but also need to configure a few things:
Figure 3-41 tracking code
which represents the auto Cookie automatically generated under the top-level domain, i.e. two sub-domains may share the same top-level domain is inside the Cookie.
If you are using GTM management, configuration CookieDomain directly on the line, this role is in front of auto, setting shown in Figure 3-42:
Figure 3-42 Configuration CookieDomain
The above two methods are the same actions, the next step is referral traffic ruled out, so that when visitors subdomain jump or the continuation of the original session without creating a new session, set the location of choice in the GA " management "→" tracking information "→" referral exclusion list "→" Add referral list ", the specific configuration shown in Figure 3-43:
Figure 3-43 referral exclusions list
With this setting, the new user session will not be generated in different subdomains jump. If no what would happen?
Consider the following example:
a user access: HTTP: // blog.ichdata.com
then visit: HTTP: // new.ichdata.com
Last access: HTTP: // blog.ichdata.com
CookieDomain and referral traffic is not set, will record two users, three sessions
If the Cookie domain, but there is no set referral traffic, will record a user, three sessions
if Cookie domain and referral traffic are set up, will record a user, a conversation
so Cross-domain configuration must be done to rule out referral list configuration.