* kubedns & kubedns-autoscaler: Stick to master nodes.
- Tolerate only master nodes and not any NoSchedule taint
- Pods are on different nodes
- Pods are required to be on a master node.
* kubedns: use soft nodeAffinity.
Prefer to be on a master node, don't require.
* coredns: Stick to (different) master nodes.
- Pods are on different nodes
- Pods are preferred to be on a master node.