> For the complete documentation index, see [llms.txt](https://docs.jentis.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.jentis.com/key-features/main-domain-cookie/why-does-it-matter-which-level-the-cookie-is-set.md). # Why does it matter which level the cookie is set? Imagine a user starts their journey on `shop.example.com` and later visits `blog.example.com`. If cookies are set at the subdomain level, their session won’t carry over, making capturing their interactions across these different subdomains difficult. This fragmentation disrupts your ability to analyze cross-domain behavior. The same happens on journeys between subdomains and the main domain. If a user starts their journey on `shop.example.com` and then visits `example.com` with cookies set at the subdomain level (`shop.example.com`), capturing their interactions across both of them won’t be possible. By setting cookies at the main domain level (e.g., `.example.com`), data can be shared across all subdomains. This ensures consistent user sessions, unified tracking, and a clearer understanding of how users engage with your entire digital ecosystem. > The **Main Domain Cookie** feature in JENTIS allows you to configure whether first-party identifiers are implemented at the main domain or subdomain level. This flexibility is essential for businesses managing multiple websites within the same main domain. With just one click, all data can be shared across the main domain and all its subdomains, ensuring consistent user sessions, unified tracking, and a clearer understanding of how users engage with your entire digital ecosystem. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://docs.jentis.com/key-features/main-domain-cookie/why-does-it-matter-which-level-the-cookie-is-set.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.