At any time you can view a list of scanner IP addresses that must be whitelisted for perimeter scanning, and a list of URLs that your scanner appliances must be able to contact for internal scanning.
Log into your Qualys account and go to Help > About.
The About page provides important details about the scanners associated with your account.
1 - Qualys External Scanners
Perimeter IPs can be scanned using our cloud scanners, also referred to as external scanners. The external scanner IPs are listed on the About page. It may be necessary to add these IPs to your list of trusted IPs, so that the service can send probes to target hosts without being blocked.
2 - Qualys Scanner Appliances
Scanning an internal network requires scanner appliances installed inside your network perimeter. The scanner appliances in your account must be able to send probes to target hosts on your internal network. Your scanner appliances must be able to contact the URLs listed on the About page via HTTPS on port 443.