diff --git a/README.md b/README.md
index b7bb24a..dadc678 100644
--- a/README.md
+++ b/README.md
@@ -71,7 +71,7 @@ Type: `string`
 
 ### <a name="input_zone"></a> [zone](#input\_zone)
 
-Description: (Required) Specifies the Availability Zone in which this Managed Disk should be located. Changing this property forces a new resource to be created.
+Description: (Optional) Specifies the Availability Zone in which this Managed Disk should be located. Changing this property forces a new resource to be created.  Note that the availability zone number here are the logical availability zone in your Azure subscription. Different subscriptions might have a different mapping of the physical zone and logical zone. To understand more, please refer to [Physical and logical availability zones](https://learn.microsoft.com/en-us/azure/reliability/availability-zones-overview?tabs=azure-cli#physical-and-logical-availability-zones) and [Distribute VMs and disks across availability zones](https://learn.microsoft.com/en-us/azure/virtual-machines/disks-high-availability#distribute-vms-and-disks-across-availability-zones)
 
 Type: `string`
 
diff --git a/variables.tf b/variables.tf
index e5b9021..9c8e751 100644
--- a/variables.tf
+++ b/variables.tf
@@ -44,7 +44,7 @@ variable "storage_account_type" {
 
 variable "zone" {
   type        = string
-  description = "(Required) Specifies the Availability Zone in which this Managed Disk should be located. Changing this property forces a new resource to be created."
+  description = "(Optional) Specifies the Availability Zone in which this Managed Disk should be located. Changing this property forces a new resource to be created.  Note that the availability zone number here are the logical availability zone in your Azure subscription. Different subscriptions might have a different mapping of the physical zone and logical zone. To understand more, please refer to [Physical and logical availability zones](https://learn.microsoft.com/en-us/azure/reliability/availability-zones-overview?tabs=azure-cli#physical-and-logical-availability-zones) and [Distribute VMs and disks across availability zones](https://learn.microsoft.com/en-us/azure/virtual-machines/disks-high-availability#distribute-vms-and-disks-across-availability-zones)"
 }
 
 # required AVM interfaces