The first question on this practice test in the CKA course has you attempt to fix the webapp-mysql application that is failing to connect to the database pod. I edited the db hostname environment variable in the webapp spec of the deployment to match the name of the mysql-service, and the app page now displays as green, but when I check my results it says I have not completed the task.
Practice Test: https://kodekloud.com/courses/539883/lectures/9816836
Edit: It looks like the only solution the test accepts is to change the name of the service, rather than changing the hostname the webapp uses to lookup the service.