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Additional Information on CoreDNS in EKS Auto Mode #1149

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pgasca merged 3 commits into from
Oct 29, 2025
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Additional Information on CoreDNS in EKS Auto Mode #1149

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Additional Information on CoreDNS in EKS Auto Mode
cdirubbio Oct 29, 2025
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pgasca Oct 29, 2025
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pgasca Oct 29, 2025
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7 changes: 7 additions & 0 deletions latest/ug/automode/auto-networking.adoc
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Expand Up @@ -86,3 +86,10 @@ For more information, see <<auto-configure-alb>> or <<auto-configure-nlb>>.
* {aws} does not support migrating load balancers from the self managed {aws} load balancer controller to management by EKS Auto Mode.
* The `networking.ingress.ipBlock` field in `TargetGroupBinding` spec is not supported.
* If your worker nodes use custom security groups (not `eks-cluster-sg-*` naming pattern), your cluster role needs additional IAM permissions. The default EKS-managed policy only allows EKS to modify security groups named `eks-cluster-sg-*`. Without permission to modify your custom security groups, EKS cannot add the required ingress rules that allow ALB/NLB traffic to reach your pods.

[#dns-consider]
==== CoreDNS considerations

EKS Auto Mode does not use the traditional CoreDNS deployment to provide DNS resolution within the cluster. Instead, Auto Mode nodes utilize CoreDNS running as a system service directly on each node. If transitioning a traditional cluster to Auto Mode, you can remove the CoreDNS deployment from your cluster once your workloads have been moved to the Auto Mode nodes.

IMPORTANT: If you plan to maintain a cluster with both Auto Mode and non-Auto Mode nodes, you must retain the CoreDNS deployment. Non-Auto Mode nodes rely on the traditional CoreDNS pods for DNS resolution, as they cannot access the node-level DNS service that Auto Mode provides.