**To modify a DB subnet group** The following ``modify-db-subnet-group`` example adds a subnet with the ID ``subnet-08e41f9e230222222`` to the DB subnet group named ``mysubnetgroup``. To keep the existing subnets in the subnet group, include their IDs as values in the ``--subnet-ids`` option. Make sure to have subnets with at least two different Availability Zones in the DB subnet group. :: aws rds modify-db-subnet-group \ --db-subnet-group-name mysubnetgroup \ --subnet-ids '["subnet-0a1dc4e1a6f123456","subnet-070dd7ecb3aaaaaaa","subnet-00f5b198bc0abcdef","subnet-08e41f9e230222222"]' Output:: { "DBSubnetGroup": { "DBSubnetGroupName": "mysubnetgroup", "DBSubnetGroupDescription": "test DB subnet group", "VpcId": "vpc-0f08e7610a1b2c3d4", "SubnetGroupStatus": "Complete", "Subnets": [ { "SubnetIdentifier": "subnet-08e41f9e230222222", "SubnetAvailabilityZone": { "Name": "us-west-2a" }, "SubnetStatus": "Active" }, { "SubnetIdentifier": "subnet-070dd7ecb3aaaaaaa", "SubnetAvailabilityZone": { "Name": "us-west-2b" }, "SubnetStatus": "Active" }, { "SubnetIdentifier": "subnet-00f5b198bc0abcdef", "SubnetAvailabilityZone": { "Name": "us-west-2d" }, "SubnetStatus": "Active" }, { "SubnetIdentifier": "subnet-0a1dc4e1a6f123456", "SubnetAvailabilityZone": { "Name": "us-west-2b" }, "SubnetStatus": "Active" } ], "DBSubnetGroupArn": "arn:aws:rds:us-west-2:534026745191:subgrp:mysubnetgroup" } } For more information, see `Step 3: Create a DB Subnet Group `__ in the *Amazon RDS User Guide*.