diff --git a/specification/redis/resource-manager/Microsoft.Cache/stable/2020-06-01/redis.json b/specification/redis/resource-manager/Microsoft.Cache/stable/2020-06-01/redis.json
index 350f2ffac79d..5100af998638 100644
--- a/specification/redis/resource-manager/Microsoft.Cache/stable/2020-06-01/redis.json
+++ b/specification/redis/resource-manager/Microsoft.Cache/stable/2020-06-01/redis.json
@@ -1935,7 +1935,11 @@
         "staticIP": {
           "type": "string",
           "pattern": "^\\d+\\.\\d+\\.\\d+\\.\\d+$",
-          "description": "Static IP address. Required when deploying a Redis cache inside an existing Azure Virtual Network."
+          "description": "Static IP address. Optionally, may be specified when deploying a Redis cache inside an existing Azure Virtual Network; auto assigned by default.",
+          "x-ms-mutability": [
+            "read",
+            "create"
+          ]
         }
       },
       "required": [
diff --git a/specification/redis/resource-manager/Microsoft.Cache/stable/2020-12-01/redis.json b/specification/redis/resource-manager/Microsoft.Cache/stable/2020-12-01/redis.json
index 39379a545f35..2a847143e546 100644
--- a/specification/redis/resource-manager/Microsoft.Cache/stable/2020-12-01/redis.json
+++ b/specification/redis/resource-manager/Microsoft.Cache/stable/2020-12-01/redis.json
@@ -1947,7 +1947,11 @@
         "staticIP": {
           "type": "string",
           "pattern": "^\\d+\\.\\d+\\.\\d+\\.\\d+$",
-          "description": "Static IP address. Required when deploying a Redis cache inside an existing Azure Virtual Network."
+          "description": "Static IP address. Optionally, may be specified when deploying a Redis cache inside an existing Azure Virtual Network; auto assigned by default.",
+          "x-ms-mutability": [
+            "read",
+            "create"
+          ]
         }
       },
       "required": [