The Registrar Data Form has a section where registrars may specify the IP subnets that will be accessing the Production SRS. If you wish to change the IP subnets after this form has been submitted, please follow the .aero IP Subnet Change Request process. The specified subnets must conform to the following rules:

• A maximum of three IP subnets.

• A maximum of 96 hosts between the three IP subnets.

• The ranges must be written in CIDR format (e.g., 192.168.1.0/27 where the "/27" represents the length of the subnet). We cannot accept any ranges below a /26 range (i.e., /25, /24, etc). CIDR format dictates the number of hosts within each range. The ranges are as follows:

• /26 = 64 hosts.

• /27 = 32 hosts.

• /28 = 16 hosts.

• /29 = 8 hosts.

• /30 = 4 hosts.

• /31 = 2 hosts.

• /32 = 1 host.

• Examples of valid subnets include:

• One subnet of 64 hosts (e.g., 192.168.1.0/26).

• One subnet of 64 hosts and one subnet of 32 hosts or less (e.g., subnet #1 as 192.168.2.0/26, which represents 64 addresses 192.168.2.0 to 192.168.2.63; and subnet #2 as 192.168.3.0/27, which represents 32 addresses 192.168.3.0 to 192.168.3.31).

• Three subnets of 32 hosts or less (e.g., subnet #1 as 192.168.2.0/27, which represents 32 addresses 192.168.2.0 to 192.168.2.31; subnet #2 as 192.168.3.0/27, which represents 32 addresses 192.168.3.0 to 192.168.3.31; and subnet #3 as 192.168.4.0/27, which represents 32 addresses 192.168.4.0 to 192.168.4.31).

• The specified subnets must fall on valid bit boundaries. For example, a subnet specified as 192.168.2.1/27 is not acceptable because ".1" is not a valid boundary for a /27 subnet. The following table defines the valid boundaries for each subnet length.