# Required parameter settings for active-active clusters
<a name="mysql-active-active-clusters-parameters"></a>

Configuring parameters for active-active clusters in Amazon RDS for MySQL is essential for maintaining consistent performance and operational stability. This table details the key parameters that control replication, conflict resolution, and workload distribution. Correct configuration ensures efficient synchronization between nodes, minimizes replication lag, and optimizes resource utilization in distributed or high-traffic environments.


| Parameter | Description | Required setting | 
| --- | --- | --- | 
|  `binlog_format`  |  Sets the binary logging format. The default value for RDS for MySQL 8.0 versions and lower is `MIXED`. The default value for RDS for MySQL 8.4 versions is `ROW`. For more information, see [ the MySQL documentation](https://dev.mysql.com/doc/refman/8.0/en/replication-options-binary-log.html#sysvar_binlog_format).  |  `ROW`  | 
|  `enforce_gtid_consistency`  |  Enforces GTID consistency for statement execution. The default value for RDS for MySQL is `OFF`. For more information, see [ the MySQL documentation](https://dev.mysql.com/doc/refman/8.0/en/replication-options-gtids.html#sysvar_enforce_gtid_consistency).  |  `ON`  | 
|  `group_replication_group_name`  |  Sets the Group Replication name to a UUID. The UUID format is `11111111-2222-3333-4444-555555555555`. You can generate a MySQL UUID by connecting to a MySQL DB instance and running `SELECT UUID()`. The value must be the same for all of the DB instances in the active-active cluster. For more information, see [ the MySQL documentation](https://dev.mysql.com/doc/refman/8.0/en/miscellaneous-functions.html#function_uuid).  |  A MySQL UUID  | 
|  `gtid-mode`  |  Controls GTID-based logging. The default value for RDS for MySQL is `OFF_PERMISSIVE`. For more information, see [ the MySQL documentation](https://dev.mysql.com/doc/refman/8.0/en/replication-options-gtids.html#sysvar_gtid_mode).  |  `ON`  | 
|  `rds.custom_dns_resolution`  |  Specifies whether to allow DNS resolution from the Amazon DNS server in your VPC. DNS resolution must be enabled when Group Replication is enabled with the `rds.group_replication_enabled` parameter. DNS resolution can't be enabled when Group Replication is disabled with the `rds.group_replication_enabled` parameter. For more information, see [ Amazon DNS server](https://docs.aws.amazon.com/vpc/latest/userguide/vpc-dns.html#AmazonDNS) in the *Amazon VPC User Guide*.  |  `1`  | 
|  `rds.group_replication_enabled`  |  Specifies whether Group Replication is enabled for a DB instance. Group Replication must be enabled on a DB instance in an active-active cluster.  |  `1`  | 
|  `replica_preserve_commit_order` (RDS for MySQL 8.4 and higher versions) or `slave_preserve_commit_order` (RDS for MySQL 8.0 versions)  |  Controls the order that transactions are committed on a replica. The default value for RDS for MySQL is `ON`. For more information, see [ the MySQL documentation](https://dev.mysql.com/doc/refman/8.0/en/replication-options-replica.html#sysvar_slave_preserve_commit_order).  |  `ON`  |