ASN (Autonomous System Number)
A unique identifier for a network operator — used to detect datacenter vs residential IPs.
An Autonomous System is a network or group of networks operated by a single organization, with a unified routing policy. Each AS has a number (e.g. AS15169 for Google, AS16509 for AWS, AS4134 for China Telecom). The ASN is the unit at which IP reputation is typically calculated — services don't blacklist individual IPs, they blacklist entire ASNs.
Cloud ASNs (AWS, GCP, Azure, Vultr, Linode, DigitalOcean) are universally flagged. Residential ASNs (Comcast, AT&T, China Telecom home broadband) are universally trusted. Mobile ASNs (T-Mobile, Verizon, China Mobile) sit somewhere in between — usually trusted but occasionally flagged for security-sensitive services.
IPCombo's per-target real IP column lets you see which ASN each target actually exited from. If a target shows an IP belonging to AS16509 (AWS), that target is going through a cloud proxy — which may be blacklisted by the service. Switch to a residential or mobile IP in the recommended region to fix.