About CIDR blocks

CIDR blocks help facilitate routing by grouping sets (or blocks) of IP addresses into a single entry on a routing table.

As ​Akamai​ tunes and updates its network on an on-going basis, the list of CIDR blocks used for Client Access Control is also updated.

Whenever a network change affects your firewall's allow list, ​Akamai​ sends an email message to the contacts listed in your Client Access Control configuration. The message provides information about accessing the CIDR Lists application, and displays the final date for making changes.


The new CIDR block list is not applied to an application until you acknowledge the change on the CIDR Lists page. During this time the list of CIDR blocks may be updated.

Failure to acknowledge the updated list can result in reduced network performance for your application.