I explained what you'd need to do to a service to make it scalable at any level, such as having it store information in a DB, contact another service, or use a messaging queue. He then asked me if I knew what horizontally scalable meant, and it seemed somewhat insulting. Not all services are horizontally scalable without some work, and I thought he was asking the question to see if I understood this. Instead the answer he was looking for was placing the boxes it was on in an ALB/NLB, which seemed overly simplified to me, and clearly something I understood if I understood how to edit and prepare the service for scaling. Plus, he specifically asked what I'd need to do to the service, not networking or architecture. I told him I understood the difference between ALBs and NLBs and when each should be used, but he didn't ask what it was so I assumed he didn't know himself. He also asked no further questions about monitoring around scaling, so I assume it's something he hasn't done much.