diff --git a/content/rancher/v2.x/en/installation/air-gap-installation/config-rancher-for-private-reg/_index.md b/content/rancher/v2.x/en/installation/air-gap-installation/config-rancher-for-private-reg/_index.md
index 922cb3f1a63..d3dce39aef0 100644
--- a/content/rancher/v2.x/en/installation/air-gap-installation/config-rancher-for-private-reg/_index.md
+++ b/content/rancher/v2.x/en/installation/air-gap-installation/config-rancher-for-private-reg/_index.md
@@ -19,3 +19,5 @@ Rancher needs to be configured to use the private registry in order to provision
 1. Change the value to your registry (e.g. `registry.yourdomain.com:port`). Do not prefix the registry with `http://` or `https://`.
 
     ![Save]({{< baseurl >}}/img/rancher/airgap/enter-system-default-registry.png)
+
+>**Note:** If you want to configure the setting when starting the rancher/rancher container, you can use the environment variable `CATTLE_SYSTEM_DEFAULT_REGISTRY`.
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