Add Service tag disclaimer to ip-addresses.md

Author: jacegummersall

articles/azure-monitor/ip-addresses.md

@@ -18,6 +18,9 @@ Author: AaronMaxwell
 
 You can use Azure [network service tags](../virtual-network/service-tags-overview.md) to manage access if you're using Azure network security groups. If you're managing access for hybrid/on-premises resources, you can download the equivalent IP address lists as [JSON files](../virtual-network/service-tags-overview.md#discover-service-tags-by-using-downloadable-json-files), which are updated each week. To cover all the exceptions in this article, use the service tags `ActionGroup`, `ApplicationInsightsAvailability`, and `AzureMonitor`.
 
+> [!NOTE]
+> Service tags do not replace validation/authentication checks required for cross-tenant communications between a customer's azure resource and other service tag resources.
+
 ## Outgoing ports
 
 You need to open some outgoing ports in your server's firewall to allow the Application Insights SDK or Application Insights Agent to send data to the portal.