I was trying to understand the relation between Kubernetes Ingress Resource and Ingress Controller. I read that Ingress resource is mainly the rules and controller Pods route the traffic actually for Ingress rules.

I'm confused, like other Objects why Ingress resource can not spin up PODs on its own by specifying the image.

Secondly, how Ingress Object connects to actual Ingress Controller Pods to get its work done ( or say other way round). I don't see specifying any selector in the Ingress Object.

Thirdly, if the Ingress Resource gets its own IP address ( internal or external) then why Ingress Controller needs external IP address.

thanks

PS: I do not have a great knowledge of Kubernetes, please pardon if the questions sound silly.