diff --git a/blueprints/apigee/hybrid-gke/gke.tf b/blueprints/apigee/hybrid-gke/gke.tf
index 6ae38433a1..701384b941 100644
--- a/blueprints/apigee/hybrid-gke/gke.tf
+++ b/blueprints/apigee/hybrid-gke/gke.tf
@@ -20,12 +20,9 @@ module "cluster" {
   name       = "cluster"
   location   = var.region
   vpc_config = {
-    network    = module.vpc.self_link
-    subnetwork = module.vpc.subnet_self_links["${var.region}/subnet-apigee"]
-    secondary_range_names = {
-      pods     = "pods"
-      services = "services"
-    }
+    network                  = module.vpc.self_link
+    subnetwork               = module.vpc.subnet_self_links["${var.region}/subnet-apigee"]
+    secondary_range_names    = {}
     master_authorized_ranges = var.cluster_network_config.master_authorized_cidr_blocks
     master_ipv4_cidr_block   = var.cluster_network_config.master_cidr_block
   }
@@ -79,4 +76,4 @@ module "apigee-runtime-nodepool" {
     create = true
   }
   tags = ["node"]
-}
\ No newline at end of file
+}
diff --git a/blueprints/gke/autopilot/cluster.tf b/blueprints/gke/autopilot/cluster.tf
index ed6fa66122..a823a894ca 100644
--- a/blueprints/gke/autopilot/cluster.tf
+++ b/blueprints/gke/autopilot/cluster.tf
@@ -20,12 +20,9 @@ module "cluster" {
   name       = "cluster"
   location   = var.region
   vpc_config = {
-    network    = module.vpc.self_link
-    subnetwork = module.vpc.subnet_self_links["${var.region}/subnet-cluster"]
-    secondary_range_names = {
-      pods     = "pods"
-      services = "services"
-    }
+    network                  = module.vpc.self_link
+    subnetwork               = module.vpc.subnet_self_links["${var.region}/subnet-cluster"]
+    secondary_range_names    = {}
     master_authorized_ranges = var.cluster_network_config.master_authorized_cidr_blocks
     master_ipv4_cidr_block   = var.cluster_network_config.master_cidr_block
   }
@@ -51,4 +48,4 @@ module "node_sa" {
   source     = "../../../modules/iam-service-account"
   project_id = module.project.project_id
   name       = "sa-node"
-}
\ No newline at end of file
+}
diff --git a/fast/stages/3-gke-multitenant/dev/README.md b/fast/stages/3-gke-multitenant/dev/README.md
index 23572297ca..411c4bc410 100644
--- a/fast/stages/3-gke-multitenant/dev/README.md
+++ b/fast/stages/3-gke-multitenant/dev/README.md
@@ -167,7 +167,7 @@ Leave all these variables unset (or set to `null`) to disable fleet management.
 | [host_project_ids](variables.tf#L174) | Host project for the shared VPC. | <code title="object&#40;&#123;&#10;  dev-spoke-0 &#61; string&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> | ✓ |  | <code>2-networking</code> |
 | [prefix](variables.tf#L227) | Prefix used for resources that need unique names. | <code>string</code> | ✓ |  |  |
 | [vpc_self_links](variables.tf#L243) | Self link for the shared VPC. | <code title="object&#40;&#123;&#10;  dev-spoke-0 &#61; string&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> | ✓ |  | <code>2-networking</code> |
-| [clusters](variables.tf#L42) | Clusters configuration. Refer to the gke-cluster module for type details. | <code title="map&#40;object&#40;&#123;&#10;  cluster_autoscaling &#61; optional&#40;any&#41;&#10;  description         &#61; optional&#40;string&#41;&#10;  enable_addons &#61; optional&#40;any, &#123;&#10;    horizontal_pod_autoscaling &#61; true, http_load_balancing &#61; true&#10;  &#125;&#41;&#10;  enable_features &#61; optional&#40;any, &#123;&#10;    workload_identity &#61; true&#10;  &#125;&#41;&#10;  issue_client_certificate &#61; optional&#40;bool, false&#41;&#10;  labels                   &#61; optional&#40;map&#40;string&#41;&#41;&#10;  location                 &#61; string&#10;  logging_config &#61; optional&#40;object&#40;&#123;&#10;    enable_system_logs             &#61; optional&#40;bool, true&#41;&#10;    enable_workloads_logs          &#61; optional&#40;bool, true&#41;&#10;    enable_api_server_logs         &#61; optional&#40;bool, false&#41;&#10;    enable_scheduler_logs          &#61; optional&#40;bool, false&#41;&#10;    enable_controller_manager_logs &#61; optional&#40;bool, false&#41;&#10;  &#125;&#41;, &#123;&#125;&#41;&#10;  maintenance_config &#61; optional&#40;any, &#123;&#10;    daily_window_start_time &#61; &#34;03:00&#34;&#10;    recurring_window        &#61; null&#10;    maintenance_exclusion   &#61; &#91;&#93;&#10;  &#125;&#41;&#10;  max_pods_per_node  &#61; optional&#40;number, 110&#41;&#10;  min_master_version &#61; optional&#40;string&#41;&#10;  monitoring_config &#61; optional&#40;object&#40;&#123;&#10;    enable_components  &#61; optional&#40;list&#40;string&#41;, &#91;&#34;SYSTEM_COMPONENTS&#34;&#93;&#41;&#10;    managed_prometheus &#61; optional&#40;bool&#41;&#10;  &#125;&#41;&#41;&#10;  node_locations         &#61; optional&#40;list&#40;string&#41;&#41;&#10;  private_cluster_config &#61; optional&#40;any&#41;&#10;  release_channel        &#61; optional&#40;string&#41;&#10;  vpc_config &#61; object&#40;&#123;&#10;    subnetwork &#61; string&#10;    network    &#61; optional&#40;string&#41;&#10;    secondary_range_blocks &#61; optional&#40;object&#40;&#123;&#10;      pods     &#61; string&#10;      services &#61; string&#10;    &#125;&#41;&#41;&#10;    secondary_range_names &#61; optional&#40;object&#40;&#123;&#10;      pods     &#61; string&#10;      services &#61; string&#10;    &#125;&#41;, &#123; pods &#61; &#34;pods&#34;, services &#61; &#34;services&#34; &#125;&#41;&#10;    master_authorized_ranges &#61; optional&#40;map&#40;string&#41;&#41;&#10;    master_ipv4_cidr_block   &#61; optional&#40;string&#41;&#10;  &#125;&#41;&#10;&#125;&#41;&#41;">map&#40;object&#40;&#123;&#8230;&#125;&#41;&#41;</code> |  | <code>&#123;&#125;</code> |  |
+| [clusters](variables.tf#L42) | Clusters configuration. Refer to the gke-cluster module for type details. | <code title="map&#40;object&#40;&#123;&#10;  cluster_autoscaling &#61; optional&#40;any&#41;&#10;  description         &#61; optional&#40;string&#41;&#10;  enable_addons &#61; optional&#40;any, &#123;&#10;    horizontal_pod_autoscaling &#61; true, http_load_balancing &#61; true&#10;  &#125;&#41;&#10;  enable_features &#61; optional&#40;any, &#123;&#10;    workload_identity &#61; true&#10;  &#125;&#41;&#10;  issue_client_certificate &#61; optional&#40;bool, false&#41;&#10;  labels                   &#61; optional&#40;map&#40;string&#41;&#41;&#10;  location                 &#61; string&#10;  logging_config &#61; optional&#40;object&#40;&#123;&#10;    enable_system_logs             &#61; optional&#40;bool, true&#41;&#10;    enable_workloads_logs          &#61; optional&#40;bool, true&#41;&#10;    enable_api_server_logs         &#61; optional&#40;bool, false&#41;&#10;    enable_scheduler_logs          &#61; optional&#40;bool, false&#41;&#10;    enable_controller_manager_logs &#61; optional&#40;bool, false&#41;&#10;  &#125;&#41;, &#123;&#125;&#41;&#10;  maintenance_config &#61; optional&#40;any, &#123;&#10;    daily_window_start_time &#61; &#34;03:00&#34;&#10;    recurring_window        &#61; null&#10;    maintenance_exclusion   &#61; &#91;&#93;&#10;  &#125;&#41;&#10;  max_pods_per_node  &#61; optional&#40;number, 110&#41;&#10;  min_master_version &#61; optional&#40;string&#41;&#10;  monitoring_config &#61; optional&#40;object&#40;&#123;&#10;    enable_components  &#61; optional&#40;list&#40;string&#41;, &#91;&#34;SYSTEM_COMPONENTS&#34;&#93;&#41;&#10;    managed_prometheus &#61; optional&#40;bool&#41;&#10;  &#125;&#41;&#41;&#10;  node_locations         &#61; optional&#40;list&#40;string&#41;&#41;&#10;  private_cluster_config &#61; optional&#40;any&#41;&#10;  release_channel        &#61; optional&#40;string&#41;&#10;  vpc_config &#61; object&#40;&#123;&#10;    subnetwork &#61; string&#10;    network    &#61; optional&#40;string&#41;&#10;    secondary_range_blocks &#61; optional&#40;object&#40;&#123;&#10;      pods     &#61; string&#10;      services &#61; string&#10;    &#125;&#41;&#41;&#10;    secondary_range_names &#61; optional&#40;object&#40;&#123;&#10;      pods     &#61; optional&#40;string, &#34;pods&#34;&#41;&#10;      services &#61; optional&#40;string, &#34;services&#34;&#41;&#10;    &#125;&#41;&#41;&#10;    master_authorized_ranges &#61; optional&#40;map&#40;string&#41;&#41;&#10;    master_ipv4_cidr_block   &#61; optional&#40;string&#41;&#10;  &#125;&#41;&#10;&#125;&#41;&#41;">map&#40;object&#40;&#123;&#8230;&#125;&#41;&#41;</code> |  | <code>&#123;&#125;</code> |  |
 | [fleet_configmanagement_clusters](variables.tf#L96) | Config management features enabled on specific sets of member clusters, in config name => [cluster name] format. | <code>map&#40;list&#40;string&#41;&#41;</code> |  | <code>&#123;&#125;</code> |  |
 | [fleet_configmanagement_templates](variables.tf#L104) | Sets of config management configurations that can be applied to member clusters, in config name => {options} format. | <code title="map&#40;object&#40;&#123;&#10;  binauthz &#61; bool&#10;  config_sync &#61; object&#40;&#123;&#10;    git &#61; object&#40;&#123;&#10;      gcp_service_account_email &#61; string&#10;      https_proxy               &#61; string&#10;      policy_dir                &#61; string&#10;      secret_type               &#61; string&#10;      sync_branch               &#61; string&#10;      sync_repo                 &#61; string&#10;      sync_rev                  &#61; string&#10;      sync_wait_secs            &#61; number&#10;    &#125;&#41;&#10;    prevent_drift &#61; string&#10;    source_format &#61; string&#10;  &#125;&#41;&#10;  hierarchy_controller &#61; object&#40;&#123;&#10;    enable_hierarchical_resource_quota &#61; bool&#10;    enable_pod_tree_labels             &#61; bool&#10;  &#125;&#41;&#10;  policy_controller &#61; object&#40;&#123;&#10;    audit_interval_seconds     &#61; number&#10;    exemptable_namespaces      &#61; list&#40;string&#41;&#10;    log_denies_enabled         &#61; bool&#10;    referential_rules_enabled  &#61; bool&#10;    template_library_installed &#61; bool&#10;  &#125;&#41;&#10;  version &#61; string&#10;&#125;&#41;&#41;">map&#40;object&#40;&#123;&#8230;&#125;&#41;&#41;</code> |  | <code>&#123;&#125;</code> |  |
 | [fleet_features](variables.tf#L139) | Enable and configure fleet features. Set to null to disable GKE Hub if fleet workload identity is not used. | <code title="object&#40;&#123;&#10;  appdevexperience             &#61; bool&#10;  configmanagement             &#61; bool&#10;  identityservice              &#61; bool&#10;  multiclusteringress          &#61; string&#10;  multiclusterservicediscovery &#61; bool&#10;  servicemesh                  &#61; bool&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> |  | <code>null</code> |  |
diff --git a/fast/stages/3-gke-multitenant/dev/variables.tf b/fast/stages/3-gke-multitenant/dev/variables.tf
index 11e32ed6ae..dffca0bf22 100644
--- a/fast/stages/3-gke-multitenant/dev/variables.tf
+++ b/fast/stages/3-gke-multitenant/dev/variables.tf
@@ -1,5 +1,5 @@
 /**
- * Copyright 2022 Google LLC
+ * Copyright 2023 Google LLC
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -82,9 +82,9 @@ variable "clusters" {
         services = string
       }))
       secondary_range_names = optional(object({
-        pods     = string
-        services = string
-      }), { pods = "pods", services = "services" })
+        pods     = optional(string, "pods")
+        services = optional(string, "services")
+      }))
       master_authorized_ranges = optional(map(string))
       master_ipv4_cidr_block   = optional(string)
     })
diff --git a/modules/gke-cluster-autopilot/README.md b/modules/gke-cluster-autopilot/README.md
index a110e8f748..2c0083108f 100644
--- a/modules/gke-cluster-autopilot/README.md
+++ b/modules/gke-cluster-autopilot/README.md
@@ -64,7 +64,7 @@ module "cluster-1" {
   vpc_config = {
     network               = var.vpc.self_link
     subnetwork            = var.subnet.self_link
-    secondary_range_names = { pods = "pods", services = "services" }
+    secondary_range_names = {} # use default names "pods" and "services"
   }
   enable_features = {
     dns = {
@@ -91,8 +91,9 @@ module "cluster-1" {
   name       = "cluster-1"
   location   = "europe-west1"
   vpc_config = {
-    network    = var.vpc.self_link
-    subnetwork = var.subnet.self_link
+    network               = var.vpc.self_link
+    subnetwork            = var.subnet.self_link
+    secondary_range_names = {} # use default names "pods" and "services"
   }
   logging_config = {
     enable_api_server_logs         = true
@@ -120,8 +121,9 @@ module "cluster-1" {
   name       = "cluster-1"
   location   = "europe-west1"
   vpc_config = {
-    network    = var.vpc.self_link
-    subnetwork = var.subnet.self_link
+    network               = var.vpc.self_link
+    subnetwork            = var.subnet.self_link
+    secondary_range_names = {} # use default names "pods" and "services"
   }
   monitoring_config = {
     enable_api_server_metrics         = true
@@ -155,7 +157,7 @@ module "cluster-1" {
   vpc_config = {
     network               = var.vpc.self_link
     subnetwork            = var.subnet.self_link
-    secondary_range_names = { pods = "pods", services = "services" }
+    secondary_range_names = {}
   }
   backup_configs = {
     enable_backup_agent = true
@@ -177,7 +179,7 @@ module "cluster-1" {
 | [location](variables.tf#L110) | Autopilot cluster are always regional. | <code>string</code> | ✓ |  |
 | [name](variables.tf#L170) | Cluster name. | <code>string</code> | ✓ |  |
 | [project_id](variables.tf#L196) | Cluster project id. | <code>string</code> | ✓ |  |
-| [vpc_config](variables.tf#L225) | VPC-level configuration. | <code title="object&#40;&#123;&#10;  network                &#61; string&#10;  subnetwork             &#61; string&#10;  master_ipv4_cidr_block &#61; optional&#40;string&#41;&#10;  secondary_range_blocks &#61; optional&#40;object&#40;&#123;&#10;    pods     &#61; string&#10;    services &#61; string&#10;  &#125;&#41;&#41;&#10;  secondary_range_names &#61; optional&#40;object&#40;&#123;&#10;    pods     &#61; string&#10;    services &#61; string&#10;  &#125;&#41;, &#123; pods &#61; &#34;pods&#34;, services &#61; &#34;services&#34; &#125;&#41;&#10;  master_authorized_ranges &#61; optional&#40;map&#40;string&#41;&#41;&#10;  stack_type               &#61; optional&#40;string&#41;&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> | ✓ |  |
+| [vpc_config](variables.tf#L225) | VPC-level configuration. | <code title="object&#40;&#123;&#10;  network                &#61; string&#10;  subnetwork             &#61; string&#10;  master_ipv4_cidr_block &#61; optional&#40;string&#41;&#10;  secondary_range_blocks &#61; optional&#40;object&#40;&#123;&#10;    pods     &#61; string&#10;    services &#61; string&#10;  &#125;&#41;&#41;&#10;  secondary_range_names &#61; optional&#40;object&#40;&#123;&#10;    pods     &#61; optional&#40;string, &#34;pods&#34;&#41;&#10;    services &#61; optional&#40;string, &#34;services&#34;&#41;&#10;  &#125;&#41;&#41;&#10;  master_authorized_ranges &#61; optional&#40;map&#40;string&#41;&#41;&#10;  stack_type               &#61; optional&#40;string&#41;&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> | ✓ |  |
 | [backup_configs](variables.tf#L17) | Configuration for Backup for GKE. | <code title="object&#40;&#123;&#10;  enable_backup_agent &#61; optional&#40;bool, false&#41;&#10;  backup_plans &#61; optional&#40;map&#40;object&#40;&#123;&#10;    encryption_key                    &#61; optional&#40;string&#41;&#10;    include_secrets                   &#61; optional&#40;bool, true&#41;&#10;    include_volume_data               &#61; optional&#40;bool, true&#41;&#10;    namespaces                        &#61; optional&#40;list&#40;string&#41;&#41;&#10;    region                            &#61; string&#10;    schedule                          &#61; string&#10;    retention_policy_days             &#61; optional&#40;string&#41;&#10;    retention_policy_lock             &#61; optional&#40;bool, false&#41;&#10;    retention_policy_delete_lock_days &#61; optional&#40;string&#41;&#10;  &#125;&#41;&#41;, &#123;&#125;&#41;&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> |  | <code>&#123;&#125;</code> |
 | [description](variables.tf#L37) | Cluster description. | <code>string</code> |  | <code>null</code> |
 | [enable_addons](variables.tf#L43) | Addons enabled in the cluster (true means enabled). | <code title="object&#40;&#123;&#10;  cloudrun                   &#61; optional&#40;bool, false&#41;&#10;  config_connector           &#61; optional&#40;bool, false&#41;&#10;  dns_cache                  &#61; optional&#40;bool, false&#41;&#10;  horizontal_pod_autoscaling &#61; optional&#40;bool, false&#41;&#10;  http_load_balancing        &#61; optional&#40;bool, false&#41;&#10;  istio &#61; optional&#40;object&#40;&#123;&#10;    enable_tls &#61; bool&#10;  &#125;&#41;&#41;&#10;  kalm           &#61; optional&#40;bool, false&#41;&#10;  network_policy &#61; optional&#40;bool, false&#41;&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> |  | <code title="&#123;&#10;  horizontal_pod_autoscaling &#61; true&#10;  http_load_balancing        &#61; true&#10;&#125;">&#123;&#8230;&#125;</code> |
diff --git a/modules/gke-cluster-autopilot/main.tf b/modules/gke-cluster-autopilot/main.tf
index 13317f469b..9af26acdf8 100644
--- a/modules/gke-cluster-autopilot/main.tf
+++ b/modules/gke-cluster-autopilot/main.tf
@@ -108,7 +108,7 @@ resource "google_container_cluster" "cluster" {
     content {
       cluster_ipv4_cidr_block  = var.vpc_config.secondary_range_blocks.pods
       services_ipv4_cidr_block = var.vpc_config.secondary_range_blocks.services
-      stack_type               = try(var.vpc_config.stack_type, null)
+      stack_type               = var.vpc_config.stack_type
     }
   }
 
@@ -117,7 +117,7 @@ resource "google_container_cluster" "cluster" {
     content {
       cluster_secondary_range_name  = var.vpc_config.secondary_range_names.pods
       services_secondary_range_name = var.vpc_config.secondary_range_names.services
-      stack_type                    = try(var.vpc_config.stack_type, null)
+      stack_type                    = var.vpc_config.stack_type
     }
   }
 
diff --git a/modules/gke-cluster-autopilot/variables.tf b/modules/gke-cluster-autopilot/variables.tf
index 3f623347d9..37c054e344 100644
--- a/modules/gke-cluster-autopilot/variables.tf
+++ b/modules/gke-cluster-autopilot/variables.tf
@@ -233,9 +233,9 @@ variable "vpc_config" {
       services = string
     }))
     secondary_range_names = optional(object({
-      pods     = string
-      services = string
-    }), { pods = "pods", services = "services" })
+      pods     = optional(string, "pods")
+      services = optional(string, "services")
+    }))
     master_authorized_ranges = optional(map(string))
     stack_type               = optional(string)
   })
diff --git a/modules/gke-cluster-standard/README.md b/modules/gke-cluster-standard/README.md
index e80a4e6d43..0dfd6636f3 100644
--- a/modules/gke-cluster-standard/README.md
+++ b/modules/gke-cluster-standard/README.md
@@ -45,12 +45,9 @@ module "cluster-1" {
   name       = "cluster-dataplane-v2"
   location   = "europe-west1-b"
   vpc_config = {
-    network    = var.vpc.self_link
-    subnetwork = var.subnet.self_link
-    secondary_range_names = {
-      pods     = "pods"
-      services = "services"
-    }
+    network               = var.vpc.self_link
+    subnetwork            = var.subnet.self_link
+    secondary_range_names = {} # use default names "pods" and "services"
     master_authorized_ranges = {
       internal-vms = "10.0.0.0/8"
     }
@@ -84,8 +81,9 @@ module "cluster-1" {
   name       = "cluster-1"
   location   = "europe-west1-b"
   vpc_config = {
-    network    = var.vpc.self_link
-    subnetwork = var.subnet.self_link
+    network               = var.vpc.self_link
+    subnetwork            = var.subnet.self_link
+    secondary_range_names = {}
   }
   logging_config = {
     enable_workloads_logs          = true
@@ -113,8 +111,9 @@ module "cluster-1" {
   name       = "cluster-1"
   location   = "europe-west1-b"
   vpc_config = {
-    network    = var.vpc.self_link
-    subnetwork = var.subnet.self_link
+    network               = var.vpc.self_link
+    subnetwork            = var.subnet.self_link
+    secondary_range_names = {}
   }
   logging_config = {
     enable_system_logs = false
@@ -136,7 +135,7 @@ module "cluster-1" {
   vpc_config = {
     network               = var.vpc.self_link
     subnetwork            = var.subnet.self_link
-    secondary_range_names = { pods = "pods", services = "services" }
+    secondary_range_names = {}
   }
   enable_features = {
     dns = {
@@ -162,7 +161,7 @@ module "cluster-1" {
   vpc_config = {
     network               = var.vpc.self_link
     subnetwork            = var.subnet.self_link
-    secondary_range_names = { pods = "pods", services = "services" }
+    secondary_range_names = {}
   }
   backup_configs = {
     enable_backup_agent = true
@@ -176,6 +175,29 @@ module "cluster-1" {
 }
 # tftest modules=1 resources=2 inventory=backup.yaml
 ```
+
+### Automatic creation of new secondary ranges
+
+You can use `var.vpc_config.secondary_range_blocks` to let GKE create new secondary ranges for the cluster. The example below reserves an available /14 block for pods and a /20 for services.
+
+```hcl
+module "cluster-1" {
+  source     = "./fabric/modules/gke-cluster-standard"
+  project_id = var.project_id
+  name       = "cluster-1"
+  location   = "europe-west1-b"
+  vpc_config = {
+    network    = var.vpc.self_link
+    subnetwork = var.subnet.self_link
+    secondary_range_blocks = {
+      pods     = ""
+      services = "/20" # can be an empty string as well
+    }
+  }
+}
+# tftest modules=1 resources=1
+```
+
 <!-- BEGIN TFDOC -->
 ## Variables
 
@@ -184,7 +206,7 @@ module "cluster-1" {
 | [location](variables.tf#L138) | Cluster zone or region. | <code>string</code> | ✓ |  |
 | [name](variables.tf#L210) | Cluster name. | <code>string</code> | ✓ |  |
 | [project_id](variables.tf#L236) | Cluster project id. | <code>string</code> | ✓ |  |
-| [vpc_config](variables.tf#L253) | VPC-level configuration. | <code title="object&#40;&#123;&#10;  network                &#61; string&#10;  subnetwork             &#61; string&#10;  master_ipv4_cidr_block &#61; optional&#40;string&#41;&#10;  secondary_range_blocks &#61; optional&#40;object&#40;&#123;&#10;    pods     &#61; string&#10;    services &#61; string&#10;  &#125;&#41;&#41;&#10;  secondary_range_names &#61; optional&#40;object&#40;&#123;&#10;    pods     &#61; string&#10;    services &#61; string&#10;  &#125;&#41;, &#123; pods &#61; &#34;pods&#34;, services &#61; &#34;services&#34; &#125;&#41;&#10;  master_authorized_ranges &#61; optional&#40;map&#40;string&#41;&#41;&#10;  stack_type               &#61; optional&#40;string&#41;&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> | ✓ |  |
+| [vpc_config](variables.tf#L253) | VPC-level configuration. | <code title="object&#40;&#123;&#10;  network                &#61; string&#10;  subnetwork             &#61; string&#10;  master_ipv4_cidr_block &#61; optional&#40;string&#41;&#10;  secondary_range_blocks &#61; optional&#40;object&#40;&#123;&#10;    pods     &#61; string&#10;    services &#61; string&#10;  &#125;&#41;&#41;&#10;  secondary_range_names &#61; optional&#40;object&#40;&#123;&#10;    pods     &#61; optional&#40;string, &#34;pods&#34;&#41;&#10;    services &#61; optional&#40;string, &#34;services&#34;&#41;&#10;  &#125;&#41;&#41;&#10;  master_authorized_ranges &#61; optional&#40;map&#40;string&#41;&#41;&#10;  stack_type               &#61; optional&#40;string&#41;&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> | ✓ |  |
 | [backup_configs](variables.tf#L17) | Configuration for Backup for GKE. | <code title="object&#40;&#123;&#10;  enable_backup_agent &#61; optional&#40;bool, false&#41;&#10;  backup_plans &#61; optional&#40;map&#40;object&#40;&#123;&#10;    encryption_key                    &#61; optional&#40;string&#41;&#10;    include_secrets                   &#61; optional&#40;bool, true&#41;&#10;    include_volume_data               &#61; optional&#40;bool, true&#41;&#10;    namespaces                        &#61; optional&#40;list&#40;string&#41;&#41;&#10;    region                            &#61; string&#10;    schedule                          &#61; string&#10;    retention_policy_days             &#61; optional&#40;string&#41;&#10;    retention_policy_lock             &#61; optional&#40;bool, false&#41;&#10;    retention_policy_delete_lock_days &#61; optional&#40;string&#41;&#10;  &#125;&#41;&#41;, &#123;&#125;&#41;&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> |  | <code>&#123;&#125;</code> |
 | [cluster_autoscaling](variables.tf#L37) | Enable and configure limits for Node Auto-Provisioning with Cluster Autoscaler. | <code title="object&#40;&#123;&#10;  auto_provisioning_defaults &#61; optional&#40;object&#40;&#123;&#10;    boot_disk_kms_key &#61; optional&#40;string&#41;&#10;    image_type        &#61; optional&#40;string&#41;&#10;    oauth_scopes      &#61; optional&#40;list&#40;string&#41;&#41;&#10;    service_account   &#61; optional&#40;string&#41;&#10;  &#125;&#41;&#41;&#10;  cpu_limits &#61; optional&#40;object&#40;&#123;&#10;    min &#61; number&#10;    max &#61; number&#10;  &#125;&#41;&#41;&#10;  mem_limits &#61; optional&#40;object&#40;&#123;&#10;    min &#61; number&#10;    max &#61; number&#10;  &#125;&#41;&#41;&#10;&#125;&#41;">object&#40;&#123;&#8230;&#125;&#41;</code> |  | <code>null</code> |
 | [description](variables.tf#L58) | Cluster description. | <code>string</code> |  | <code>null</code> |
diff --git a/modules/gke-cluster-standard/main.tf b/modules/gke-cluster-standard/main.tf
index 8f0df84f78..57d5454f38 100644
--- a/modules/gke-cluster-standard/main.tf
+++ b/modules/gke-cluster-standard/main.tf
@@ -169,7 +169,7 @@ resource "google_container_cluster" "cluster" {
     content {
       cluster_ipv4_cidr_block  = var.vpc_config.secondary_range_blocks.pods
       services_ipv4_cidr_block = var.vpc_config.secondary_range_blocks.services
-      stack_type               = try(var.vpc_config.stack_type, null)
+      stack_type               = var.vpc_config.stack_type
     }
   }
   dynamic "ip_allocation_policy" {
@@ -177,7 +177,7 @@ resource "google_container_cluster" "cluster" {
     content {
       cluster_secondary_range_name  = var.vpc_config.secondary_range_names.pods
       services_secondary_range_name = var.vpc_config.secondary_range_names.services
-      stack_type                    = try(var.vpc_config.stack_type, null)
+      stack_type                    = var.vpc_config.stack_type
     }
   }
 
diff --git a/modules/gke-cluster-standard/variables.tf b/modules/gke-cluster-standard/variables.tf
index b9c4a1136c..cc1cb63f17 100644
--- a/modules/gke-cluster-standard/variables.tf
+++ b/modules/gke-cluster-standard/variables.tf
@@ -261,9 +261,9 @@ variable "vpc_config" {
       services = string
     }))
     secondary_range_names = optional(object({
-      pods     = string
-      services = string
-    }), { pods = "pods", services = "services" })
+      pods     = optional(string, "pods")
+      services = optional(string, "services")
+    }))
     master_authorized_ranges = optional(map(string))
     stack_type               = optional(string)
   })