AWS EKS Windows Pod unable to resolve DNS

A possible cause for this is the incorrectly configured aws-auth configmap. Please check the aws-auth config map for any duplicate entries. Also, ensure that you have separate IAM roles for the Windows and Linux nodes.

I would like to elaborate further on AWS-User-3414175's answer. Make sure that your windows nodegroup IAM role mapping in the aws-auth ConfigMap has an additional RBAC permission group eks:kube-proxy-windows specified. Please find the sample aws-auth ConfigMap below.

Refer to https://docs.aws.amazon.com/eks/latest/userguide/launch-windows-workers.html#aws-management-console for more info.

apiVersion: v1
kind: ConfigMap
metadata:
  name: aws-auth
  namespace: kube-system
data:
  mapRoles: |
    - rolearn: ARN of instance role (not instance profile) of **Linux** node
      username: system:node:{{EC2PrivateDNSName}}
      groups:
        - system:bootstrappers
        - system:nodes
    - rolearn: ARN of instance role (not instance profile) of **Windows** node
      username: system:node:{{EC2PrivateDNSName}}
      groups:
        - system:bootstrappers
        - system:nodes
        - eks:kube-proxy-windows