Active Protection Systems* could be blocking, filtering, dropping, or modifying network packets from a PCI Certified Scan. Such behavior could affect an ASV's ability to detect vulnerabilities. 

A new subnet has been recently added for scanning services:

139.87.112.0/255.255.254.0

You can see a full list of our IP ranges that should be allowed here if you are receiving scan interference.

Please note that these IPs are specific to our scanning services.

*Active Protection Systems could include any of the following; IPS, WAF, Firewall, NGF, QoS Device, Spam Filter, etc.