I am new to kubernetes world, Can someone specify/tell/redirect as to:
what is Kubernetes CNI?
why is it used?
what are its usecases?
what are the best CNI plugins?
You can go through following blogs to understand what is CNI and why it is used:
https://thenewstack.io/kubernetes-and-cni-whats-next-making-it-easier-to-write-networking-plugins/
Following link has some good information about different type of CNI plugins available and when to use what:
https://chrislovecnm.com/kubernetes/cni/choosing-a-cni-provider/
Hope this helps.