diff --git a/main.tf b/main.tf
index f8cce74..aced442 100644
--- a/main.tf
+++ b/main.tf
@@ -104,6 +104,7 @@ module "load_balancer" {
 
   resource_name_prefix = var.resource_name_prefix
   resource_group_name  = azurerm_resource_group.graphdb.name
+  zones                = var.zones
 
   tags = local.tags
 
@@ -125,6 +126,7 @@ module "vm" {
   resource_name_prefix   = var.resource_name_prefix
   resource_group_name    = azurerm_resource_group.graphdb.name
   network_interface_name = azurerm_virtual_network.graphdb.name
+  zones                  = var.zones
 
   graphdb_subnet_name                   = azurerm_subnet.graphdb-vmss.name
   load_balancer_backend_address_pool_id = module.load_balancer.load_balancer_backend_address_pool_id
diff --git a/modules/configuration/variables.tf b/modules/configuration/variables.tf
index 064d6f2..a3de37d 100644
--- a/modules/configuration/variables.tf
+++ b/modules/configuration/variables.tf
@@ -1,3 +1,5 @@
+# General configurations
+
 variable "tags" {
   description = "Common resource tags."
   type        = map(string)
@@ -9,6 +11,8 @@ variable "resource_group_name" {
   type        = string
 }
 
+# Dependencies
+
 variable "identity_name" {
   description = "Name of a user assigned identity for assigning permissions"
   type        = string
@@ -19,6 +23,8 @@ variable "key_vault_name" {
   type        = string
 }
 
+# GraphDB configurations
+
 variable "graphdb_license_path" {
   description = "Local path to a file, containing a GraphDB Enterprise license."
   type        = string
diff --git a/modules/load_balancer/variables.tf b/modules/load_balancer/variables.tf
index e7fd2eb..9f740dd 100644
--- a/modules/load_balancer/variables.tf
+++ b/modules/load_balancer/variables.tf
@@ -1,8 +1,16 @@
+# General configurations
+
 variable "resource_name_prefix" {
   description = "Resource name prefix used for tagging and naming Azure resources"
   type        = string
 }
 
+variable "zones" {
+  description = "Availability zones"
+  type        = list(number)
+  default     = [1, 2, 3]
+}
+
 variable "tags" {
   description = "Common resource tags."
   type        = map(string)
@@ -14,11 +22,7 @@ variable "resource_group_name" {
   type        = string
 }
 
-variable "zones" {
-  description = "Availability zones"
-  type        = list(number)
-  default     = [1, 2, 3]
-}
+# Load balancer specific configurations
 
 variable "backend_port" {
   description = "Backend port for the load balancer rules"
diff --git a/modules/vm/variables.tf b/modules/vm/variables.tf
index ddabc54..623a2d5 100644
--- a/modules/vm/variables.tf
+++ b/modules/vm/variables.tf
@@ -5,6 +5,12 @@ variable "resource_name_prefix" {
   type        = string
 }
 
+variable "zones" {
+  description = "Availability zones"
+  type        = list(number)
+  default     = [1, 2, 3]
+}
+
 variable "tags" {
   description = "Common resource tags."
   type        = map(string)
@@ -16,7 +22,7 @@ variable "resource_group_name" {
   type        = string
 }
 
-#
+# Networking
 
 variable "network_interface_name" {
   description = "Network interface where GraphDB will be deployed"
@@ -28,6 +34,32 @@ variable "graphdb_subnet_name" {
   type        = string
 }
 
+# Security
+
+variable "identity_name" {
+  description = "Name of a user assigned identity with permissions"
+  type        = string
+}
+
+variable "key_vault_name" {
+  description = "Name of a Key Vault containing GraphDB configurations"
+  type        = string
+}
+
+# Load balancer
+
+variable "load_balancer_backend_address_pool_id" {
+  description = "Identifier of the load balancer backend pool for GraphDB nodes"
+  type        = string
+}
+
+variable "load_balancer_fqdn" {
+  description = "FQDN of the load balancer for GraphDB"
+  type        = string
+}
+
+# GraphDB VM
+
 variable "node_count" {
   description = "Number of GraphDB nodes to deploy in ASG"
   type        = number
@@ -56,32 +88,6 @@ variable "source_ssh_blocks" {
   default     = null
 }
 
-variable "zones" {
-  description = "Availability zones"
-  type        = list(number)
-  default     = [1, 3]
-}
-
-variable "load_balancer_backend_address_pool_id" {
-  description = "Identifier of the load balancer backend pool for GraphDB nodes"
-  type        = string
-}
-
-variable "load_balancer_fqdn" {
-  description = "FQDN of the load balancer for GraphDB"
-  type        = string
-}
-
-variable "identity_name" {
-  description = "Name of a user assigned identity with permissions"
-  type        = string
-}
-
-variable "key_vault_name" {
-  description = "Name of a Key Vault containing GraphDB configurations"
-  type        = string
-}
-
 variable "custom_user_data" {
   description = "Custom user data script used during the cloud init phase in the GraphDB VMs. Should be in base64 encoding."
   type        = string
diff --git a/variables.tf b/variables.tf
index 22f84c3..0cf6270 100644
--- a/variables.tf
+++ b/variables.tf
@@ -10,6 +10,12 @@ variable "location" {
   type        = string
 }
 
+variable "zones" {
+  description = "Availability zones to use for resource deployment and HA"
+  type        = list(number)
+  default     = [1, 2, 3]
+}
+
 variable "tags" {
   description = "Common resource tags."
   type        = map(string)