diff --git a/modules/backend/README.md b/modules/backend/README.md
index bd6f5555..7fd910de 100644
--- a/modules/backend/README.md
+++ b/modules/backend/README.md
@@ -8,7 +8,7 @@ This module creates `google_compute_backend_service` resource and its dependenci
 |------|-------------|------|---------|:--------:|
 | affinity\_cookie\_ttl\_sec | Lifetime of cookies in seconds if session\_affinity is GENERATED\_COOKIE. | `number` | `null` | no |
 | backend\_bucket\_name | The name of GCS bucket which serves the traffic. | `string` | `""` | no |
-| cdn\_policy | Cloud CDN configuration for this BackendService. | <pre>object({<br>    cache_mode                      = optional(string)<br>    signed_url_cache_max_age_sec    = optional(string)<br>    default_ttl                     = optional(number)<br>    max_ttl                         = optional(number)<br>    client_ttl                      = optional(number)<br>    negative_caching                = optional(bool)<br>    serve_while_stale               = optional(number)<br>    bypass_cache_on_request_headers = optional(list(string))<br>    negative_caching_policy = optional(object({<br>      code = optional(number)<br>      ttl  = optional(number)<br>    }))<br>    cache_key_policy = optional(object({<br>      include_host           = optional(bool)<br>      include_protocol       = optional(bool)<br>      include_query_string   = optional(bool)<br>      query_string_blacklist = optional(list(string))<br>      query_string_whitelist = optional(list(string))<br>      include_http_headers   = optional(list(string))<br>      include_named_cookies  = optional(list(string))<br>    }))<br>  })</pre> | `{}` | no |
+| cdn\_policy | Cloud CDN configuration for this BackendService. | <pre>object({<br>    cache_mode                      = optional(string)<br>    signed_url_cache_max_age_sec    = optional(string)<br>    default_ttl                     = optional(number)<br>    max_ttl                         = optional(number)<br>    client_ttl                      = optional(number)<br>    negative_caching                = optional(bool)<br>    serve_while_stale               = optional(number)<br>    bypass_cache_on_request_headers = optional(list(string))<br>    negative_caching_policy = optional(object({<br>      code = optional(number)<br>      ttl  = optional(number)<br>    }))<br>    cache_key_policy = optional(object({<br>      include_host           = optional(bool)<br>      include_protocol       = optional(bool)<br>      include_query_string   = optional(bool)<br>      query_string_blacklist = optional(list(string))<br>      query_string_whitelist = optional(list(string))<br>      include_http_headers   = optional(list(string))<br>      include_named_cookies  = optional(list(string))<br>    }))<br>  })</pre> | <pre>{<br>  "cache_mode": "CACHE_ALL_STATIC",<br>  "client_ttl": 3600,<br>  "default_ttl": 3600,<br>  "max_ttl": 86400,<br>  "signed_url_cache_max_age_sec": 0<br>}</pre> | no |
 | compression\_mode | Compress text responses using Brotli or gzip compression. | `string` | `"DISABLED"` | no |
 | connection\_draining\_timeout\_sec | Time for which instance will be drained (not accept new connections, but still work to finish started). | `number` | `null` | no |
 | custom\_request\_headers | Headers that the HTTP/S load balancer should add to proxied requests. | `list(string)` | `[]` | no |
diff --git a/modules/backend/main.tf b/modules/backend/main.tf
index ede11825..ebe6f035 100644
--- a/modules/backend/main.tf
+++ b/modules/backend/main.tf
@@ -15,7 +15,8 @@
  */
 
 locals {
-  is_backend_bucket = var.backend_bucket_name != null && var.backend_bucket_name != ""
+  is_backend_bucket       = var.backend_bucket_name != null && var.backend_bucket_name != ""
+  serverless_neg_backends = local.is_backend_bucket ? [] : var.serverless_neg_backends
 }
 
 resource "google_compute_backend_service" "default" {
@@ -161,7 +162,7 @@ resource "google_compute_backend_service" "default" {
 }
 
 resource "google_compute_region_network_endpoint_group" "serverless_negs" {
-  for_each = { for serverless_neg_backend in var.serverless_neg_backends :
+  for_each = { for serverless_neg_backend in local.serverless_neg_backends :
   "neg-${var.name}-${serverless_neg_backend.service_name}-${serverless_neg_backend.region}" => serverless_neg_backend }
 
 
diff --git a/modules/backend/metadata.yaml b/modules/backend/metadata.yaml
index 1bdd4c2b..bd890051 100644
--- a/modules/backend/metadata.yaml
+++ b/modules/backend/metadata.yaml
@@ -224,7 +224,12 @@ spec:
                 include_named_cookies  = optional(list(string))
               }))
             })
-        defaultValue: {}
+        defaultValue:
+          cache_mode: CACHE_ALL_STATIC
+          client_ttl: 3600
+          default_ttl: 3600
+          max_ttl: 86400
+          signed_url_cache_max_age_sec: 0
       - name: outlier_detection
         description: Settings controlling eviction of unhealthy hosts from the load balancing pool.
         varType: |-
diff --git a/modules/backend/variables.tf b/modules/backend/variables.tf
index 9c9c0b3c..0cca6482 100644
--- a/modules/backend/variables.tf
+++ b/modules/backend/variables.tf
@@ -188,7 +188,13 @@ variable "cdn_policy" {
       include_named_cookies  = optional(list(string))
     }))
   })
-  default = {}
+  default = {
+    cache_mode                   = "CACHE_ALL_STATIC"
+    default_ttl                  = 3600
+    client_ttl                   = 3600
+    max_ttl                      = 86400
+    signed_url_cache_max_age_sec = 0
+  }
 }
 
 variable "outlier_detection" {
diff --git a/modules/frontend/metadata.yaml b/modules/frontend/metadata.yaml
index 8ad47ffb..9446c41a 100644
--- a/modules/frontend/metadata.yaml
+++ b/modules/frontend/metadata.yaml
@@ -116,7 +116,7 @@ spec:
         connections:
           - source:
               source: github.com/terraform-google-modules/terraform-google-lb-http//modules/backend
-              version: ^12.0
+              version: ">= 12.0"
             spec:
               outputExpr: backend_service_info
       - name: url_map_resource_uri