Via Webservices, the Last Modified Date (last_mod_dt) attribute of the ticket is not updated with the date and time of the user's action.
Release : 17.3
Component :
The reported issue is by design. REST APIs perform CRUD operations on single object types. If you are trying to create an activity log this action in no way will modify the last_mod_dt of the ticket. The user has to send a REST call to update the last_mod_dt. This kind of business logic needs to be on the client side. REST supports only CRUD operations. REST was not developed to emulate SOAP or CA web interface behavior. It was just to give a handle to perform basic CRUD operations on specified objects but not for handling any linked object updates i.e. if I am updating the "cr" object it will only update the "cr" object but won't do anything for any other objects which may be linked to it as it does not check for relational objects.