ipv4Prefix Count
Parameters
value
The number of IPv4 prefixes to assign to a network interface. When you specify a number of IPv4 prefixes, Amazon EC2 selects these prefixes from your existing subnet CIDR reservations, if available, or from free spaces in the subnet. By default, these will be /28 prefixes. You can't specify a count of IPv4 prefixes if you've specified one of the following: specific IPv4 prefixes, specific private IPv4 addresses, or a count of private IPv4 addresses.