From bc1b890f7441d515a06d247ea7cd52bbfe81b672 Mon Sep 17 00:00:00 2001
From: Tomoe Sugihara <468185+tomoe@users.noreply.github.com>
Date: Mon, 5 Mar 2018 05:26:52 +0900
Subject: [PATCH] Add a note on availability of tcp_syncookies syctl (#7627)

* Add a note on availability of tcp_syncookies syctl

Sysctl `net.ipv4.tcp_syncookies` is not availalbe on 4.4 kernel
as it's not namespaced yet.

* updating to use {: .note} notation

per https://kubernetes.io/docs/home/contribute/style-guide/#note
---
 docs/concepts/cluster-administration/sysctl-cluster.md | 3 +++
 1 file changed, 3 insertions(+)

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.