Sitecore Analytics uses cookies to collect the data. By default, separate cookies are set for different domains. For this reason the Analytics data is not shared between different sites of the same multiple-domain solution. Some cases may require different behavior.
To customize this behavior, add the following node to the sytem.web section in your web.config file and clear the browsers cookies for your sites after that change:
<system.web> <httpCookies domain=".domain.com"/> </system.web>
After applying the change, all cookies on the site will be created with the specified domain value. For example, the same cookie will be used both for test1.domain.com and test2.domain.com.