diff --git a/cluster/ubuntu/config-default.sh b/cluster/ubuntu/config-default.sh
index b3227f4228f..83b487e7b79 100755
--- a/cluster/ubuntu/config-default.sh
+++ b/cluster/ubuntu/config-default.sh
@@ -118,6 +118,9 @@ DNS_SERVER_IP=${DNS_SERVER_IP:-"192.168.3.10"}
 DNS_DOMAIN=${DNS_DOMAIN:-"cluster.local"}
 DNS_REPLICAS=${DNS_REPLICAS:-1}
 
+# Optional: Enable DNS horizontal autoscaler
+ENABLE_DNS_HORIZONTAL_AUTOSCALER="${KUBE_ENABLE_DNS_HORIZONTAL_AUTOSCALER:-false}"
+
 # Optional: Install Kubernetes UI
 ENABLE_CLUSTER_UI="${KUBE_ENABLE_CLUSTER_UI:-true}"