**To associate an IPv6 CIDR block with a subnet** This example associates an IPv6 CIDR block with the specified subnet. Command:: aws ec2 associate-subnet-cidr-block --subnet-id subnet-5f46ec3b --ipv6-cidr-block 2001:db8:1234:1a00::/64 Output:: { "SubnetId": "subnet-5f46ec3b", "Ipv6CidrBlockAssociation": { "Ipv6CidrBlock": "2001:db8:1234:1a00::/64", "AssociationId": "subnet-cidr-assoc-3aa54053", "Ipv6CidrBlockState": { "State": "associating" } } }