You create an Azure subscription named Sub1. In azure video

Full Certification Question

You create an Azure subscription named Sub1. In Sub1, you create a custom Azure Event Grid topic named Topic1. Next, you create an Event Grid event subscription named EventSub1. EventSub1 uses Topic1 as the event source and a Web Hook as the endpoint. You plan to enable dead-lettering in EventSub1. You need to ensure that you can enable dead-lettering in EventSub1. What should you do first?