AWS eks documentation change

Service: eks · 2026-01-25 · Documentation low

File: eks/latest/userguide/create-node-class.md

Summary

Added documentation for 'Secondary IP Mode for Pods' with `ipv4PrefixSize` configuration and example YAML

Security assessment

Introduces a networking configuration option for optimizing IP usage but does not directly address security vulnerabilities or security features. The change focuses on operational efficiency rather than security.

Diff

diff --git a/eks/latest/userguide/create-node-class.md b/eks/latest/userguide/create-node-class.md
index 944871a84..873a1f792 100644
--- a//eks/latest/userguide/create-node-class.md
+++ b//eks/latest/userguide/create-node-class.md
@@ -5 +5 @@
-Create a Node ClassCreate node class access entryNode Class SpecificationConsiderationsSubnet selection for Pods
+Create a Node ClassCreate node class access entryNode Class SpecificationConsiderationsSubnet selection for PodsSecondary IP Mode for Pods
@@ -86 +86 @@ Update the following CLI commands with your cluster name, and node role ARN. The
-      --policy-arn <shared id="region.arn"/>eks::aws:cluster-access-policy/AmazonEKSAutoNodePolicy \
+      --policy-arn arn:aws:eks::aws:cluster-access-policy/AmazonEKSAutoNodePolicy \
@@ -105 +105 @@ Update the following CloudFormation with your cluster name, and node role ARN. T
-            PolicyArn: <shared id="region.arn"/>eks::aws:cluster-access-policy/AmazonEKSAutoNodePolicy
+            PolicyArn: arn:aws:eks::aws:cluster-access-policy/AmazonEKSAutoNodePolicy
@@ -175 +175 @@ For information about deploying CloudFormation stacks, see [Getting started with
-        kmsKeyID: "<shared id="region.arn"/>kms:region:account:key/key-id"
+        kmsKeyID: "arn:aws:kms:region:account:key/key-id"
@@ -200,0 +201,2 @@ For information about deploying CloudFormation stacks, see [Getting started with
+        # ipv4PrefixSize is default to Auto which is prefix and fallback to secondary IP. "32" is the secondary IP mode.
+        ipv4PrefixSize: Auto # or "32"
@@ -309,0 +312,37 @@ Use `podSubnetSelectorTerms` when you need to:
+## Secondary IP Mode for Pods
+
+The `ipv4PrefixSize` fields enables advanced networking configurations by allowing only allocating secondary IP addresses to nodes. This feature doesn’t allocate prefix (/28) to nodes and maintain only one secondary IP as MinimalIPTarget.
+
+### Use cases
+
+Use `ipv4PrefixSize` when you need to:
+
+  * **Reduced IP utilization** : Only one IP addresses will be warmed up in every node.
+
+  * **Lower pods churning rate** : Pods creation velocity is not a major concern.
+
+  * **No prefix fragmentation** : Prefix caused fragmentation is a major concern or blocker to use Auto mode.
+
+
+
+
+### Example configuration
+    
+    
+    apiVersion: eks.amazonaws.com/v1
+    kind: NodeClass
+    metadata:
+      name: advanced-networking
+    spec:
+      role: MyNodeRole
+    
+      advancedNetworking:
+        ipv4PrefixSize: "32"
+
+### Considerations for secondary IP mode
+
+  * **Reduced Pod creation velocity** : Since only one secondary IP is warmed up, the IPAM service need more time to provision IPs on more pods creation.
+
+
+
+