diff --git a/README.md b/README.md
index f81a660..da55b6d 100644
--- a/README.md
+++ b/README.md
@@ -289,6 +289,7 @@ Available targets:
 | <a name="input_target_security_group_id"></a> [target\_security\_group\_id](#input\_target\_security\_group\_id) | The ID of an existing Security Group to which Security Group rules will be assigned.<br>The Security Group's name and description will not be changed.<br>Not compatible with `inline_rules_enabled` or `revoke_rules_on_delete`.<br>If not provided (the default), this module will create a security group. | `list(string)` | `[]` | no |
 | <a name="input_tenant"></a> [tenant](#input\_tenant) | ID element \_(Rarely used, not included by default)\_. A customer identifier, indicating who this instance of a resource is for | `string` | `null` | no |
 | <a name="input_transit_encryption_enabled"></a> [transit\_encryption\_enabled](#input\_transit\_encryption\_enabled) | Set `true` to enable encryption in transit. Forced `true` if `var.auth_token` is set.<br>If this is enabled, use the [following guide](https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/in-transit-encryption.html#connect-tls) to access redis. | `bool` | `true` | no |
+| <a name="input_transit_encryption_mode"></a> [transit\_encryption\_mode](#input\_transit\_encryption\_mode) | A setting that enables clients to migrate to in-transit encryption with no downtime. Valid values are `preferred` and `required`. When enabling encryption on an existing replication group, this must first be set to `preferred` before setting it to `required` in a subsequent apply. See the TransitEncryptionMode field in the [CreateReplicationGroup](https://docs.aws.amazon.com/AmazonElastiCache/latest/APIReference/API_CreateReplicationGroup.html) API documentation for additional details." | `string` | `"preferred"` | no |
 | <a name="input_use_existing_security_groups"></a> [use\_existing\_security\_groups](#input\_use\_existing\_security\_groups) | DEPRECATED: Use `create_security_group` instead.<br>Historical description: Flag to enable/disable creation of Security Group in the module.<br>Set to `true` to disable Security Group creation and provide a list of existing security Group IDs in `existing_security_groups` to place the cluster into.<br>Historical default: `false` | `bool` | `null` | no |
 | <a name="input_user_group_ids"></a> [user\_group\_ids](#input\_user\_group\_ids) | User Group ID to associate with the replication group | `list(string)` | `null` | no |
 | <a name="input_vpc_id"></a> [vpc\_id](#input\_vpc\_id) | VPC ID | `string` | n/a | yes |
diff --git a/docs/terraform.md b/docs/terraform.md
index 202a868..5670202 100644
--- a/docs/terraform.md
+++ b/docs/terraform.md
@@ -117,6 +117,7 @@
 | <a name="input_target_security_group_id"></a> [target\_security\_group\_id](#input\_target\_security\_group\_id) | The ID of an existing Security Group to which Security Group rules will be assigned.<br>The Security Group's name and description will not be changed.<br>Not compatible with `inline_rules_enabled` or `revoke_rules_on_delete`.<br>If not provided (the default), this module will create a security group. | `list(string)` | `[]` | no |
 | <a name="input_tenant"></a> [tenant](#input\_tenant) | ID element \_(Rarely used, not included by default)\_. A customer identifier, indicating who this instance of a resource is for | `string` | `null` | no |
 | <a name="input_transit_encryption_enabled"></a> [transit\_encryption\_enabled](#input\_transit\_encryption\_enabled) | Set `true` to enable encryption in transit. Forced `true` if `var.auth_token` is set.<br>If this is enabled, use the [following guide](https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/in-transit-encryption.html#connect-tls) to access redis. | `bool` | `true` | no |
+| <a name="input_transit_encryption_mode"></a> [transit\_encryption\_mode](#input\_transit\_encryption\_mode) | A setting that enables clients to migrate to in-transit encryption with no downtime. Valid values are `preferred` and `required`. When enabling encryption on an existing replication group, this must first be set to `preferred` before setting it to `required` in a subsequent apply. See the TransitEncryptionMode field in the [CreateReplicationGroup](https://docs.aws.amazon.com/AmazonElastiCache/latest/APIReference/API_CreateReplicationGroup.html) API documentation for additional details." | `string` | `"preferred"` | no |
 | <a name="input_use_existing_security_groups"></a> [use\_existing\_security\_groups](#input\_use\_existing\_security\_groups) | DEPRECATED: Use `create_security_group` instead.<br>Historical description: Flag to enable/disable creation of Security Group in the module.<br>Set to `true` to disable Security Group creation and provide a list of existing security Group IDs in `existing_security_groups` to place the cluster into.<br>Historical default: `false` | `bool` | `null` | no |
 | <a name="input_user_group_ids"></a> [user\_group\_ids](#input\_user\_group\_ids) | User Group ID to associate with the replication group | `list(string)` | `null` | no |
 | <a name="input_vpc_id"></a> [vpc\_id](#input\_vpc\_id) | VPC ID | `string` | n/a | yes |
diff --git a/examples/complete/fixtures.us-east-2.tfvars b/examples/complete/fixtures.us-east-2.tfvars
index f9faa14..62676be 100644
--- a/examples/complete/fixtures.us-east-2.tfvars
+++ b/examples/complete/fixtures.us-east-2.tfvars
@@ -15,14 +15,12 @@ instance_type = "cache.m6g.large"
 
 cluster_size = 1
 
-family = "redis6.x"
+family = "redis7"
 
-engine_version = "6.x"
+engine_version = "7.0"
 
 at_rest_encryption_enabled = false
 
 transit_encryption_enabled = true
 
-zone_id = "Z3SO0TKDDQ0RGG"
-
 cloudwatch_metric_alarms_enabled = false
diff --git a/main.tf b/main.tf
index 24a2b2b..b4c9e1f 100644
--- a/main.tf
+++ b/main.tf
@@ -178,6 +178,7 @@ resource "aws_elasticache_replication_group" "default" {
   engine_version             = var.engine_version
   at_rest_encryption_enabled = var.at_rest_encryption_enabled
   transit_encryption_enabled = var.transit_encryption_enabled
+  transit_encryption_mode    = var.transit_encryption_mode
   kms_key_id                 = var.at_rest_encryption_enabled ? var.kms_key_id : null
   snapshot_name              = var.snapshot_name
   snapshot_arns              = var.snapshot_arns
diff --git a/variables.tf b/variables.tf
index 10cc695..6e5afbb 100644
--- a/variables.tf
+++ b/variables.tf
@@ -75,6 +75,19 @@ variable "transit_encryption_enabled" {
     EOT
 }
 
+variable "transit_encryption_mode" {
+  type        = string
+  default     = "preferred"
+  description = <<-EOT
+    A setting that enables clients to migrate to in-transit encryption with no downtime. Valid values are `preferred` and `required`. When enabling encryption on an existing replication group, this must first be set to `preferred` before setting it to `required` in a subsequent apply. See the TransitEncryptionMode field in the [CreateReplicationGroup](https://docs.aws.amazon.com/AmazonElastiCache/latest/APIReference/API_CreateReplicationGroup.html) API documentation for additional details."
+    EOT
+
+  validation {
+    condition     = lower(var.transit_encryption_mode) == "preferred" || lower(var.transit_encryption_mode) == "required"
+    error_message = "The transit_encryption_mode must be either `preferred` (Default) or `required`"
+  }
+}
+
 variable "notification_topic_arn" {
   type        = string
   default     = ""