The Case entity, which is also called ticket in Microsoft Dynamics CRM, pertains to the issues and problems of customers. Therefore, whenever a customer raises an issue, the customer service agent will record it in the form of a case. These cases are routed to service agents in a queue. A case is tracked until it gets resolved.
Before assigning the case, you need to check the customer's entitlements. Through entitlements, it can be known whether the customer is eligible for a service.
You can also check if there is an existing case in the system; it can then be reopened.