diff --git a/docs/concepts/cluster-administration/sysctl-cluster.md b/docs/concepts/cluster-administration/sysctl-cluster.md
index d79a6abd07..f7b715f6c3 100644
--- a/docs/concepts/cluster-administration/sysctl-cluster.md
+++ b/docs/concepts/cluster-administration/sysctl-cluster.md
@@ -70,6 +70,9 @@ For Kubernetes 1.4, the following sysctls are supported in the _safe_ set:
 - `net.ipv4.ip_local_port_range`,
 - `net.ipv4.tcp_syncookies`.
 
+**Note**: The example `net.ipv4.tcp_syncookies` is not namespaced on Linux kernel version 4.4 or lower.
+{: .note}
+
 This list will be extended in future Kubernetes versions when the kubelet
 supports better isolation mechanisms.