> For the complete documentation index, see [llms.txt](https://cortex-docs.paloaltonetworks.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://cortex-docs.paloaltonetworks.com/cortex-xsoar-6-multi-tenant-guides/6.12/onboard-multi-tenant/plan-your-multi-tenant-deployment/communication-in-a-multi-tenant-deployment.md).

# Communication in a Multi-Tenant Deployment

In a multi-tenant deployment, communication is predominantly from the main host server to any additional host servers, and then from the hosts to the tenants. Two-way communication should always be available between the main server and host servers. The main host server and additional host servers communicate using TLS 1.2 over port 443. Requests to the tenants are sent through the hosts (main or other) on port 443. The hosts forward the requests to the tenants, which listen on ports 18501 and higher.

Port 443 is used for communication between the main host server and additional host servers.

In a high availability environment, hosts in the same high availability group communicate with each other over port 443. There is no communication between hosts in different high availability groups.

|                             | Main hosts (incoming)                                                                                                                                                   | Additional hosts (incoming)               | Tenant on main host (incoming) | Tenant on additional host (incoming) |
| --------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------- | ------------------------------ | ------------------------------------ |
| Main hosts (outgoing)       | 443 (in high availability)                                                                                                                                              | 443                                       | 1850x                          | 443                                  |
| Additional hosts (outgoing) | 443 ([configurable](/cortex-xsoar-6-multi-tenant-guides/6.12/onboard-multi-tenant/plan-your-multi-tenant-deployment/change-the-port-for-host-to-main-communication.md)) | 443 (in the same high availability group) | -                              | 1850x                                |


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