ASN Reputation
The trust score assigned to a whole network block, the basis of nearly all IP-based access decisions.
ASN reputation is the trust score that anti-abuse systems assign to an entire Autonomous System. The score is computed from observed behavior across the ASN's IP space: how many spam complaints, how many failed login attempts, how many scraper requests, how many bot-driven transactions. A single bad IP doesn't move the score much; a pattern of bad behavior across thousands of IPs drops the whole ASN. This is why services block at the ASN level rather than the IP level — the data is much more stable, and one attacker can't churn through it.
Reputation differs sharply by ASN type. Datacenter ASNs (AWS, GCP, Azure, Vultr, Linode, DigitalOcean, OVH, Hetzner) have the worst reputation — they are where attackers buy infrastructure. Residential ASNs (Comcast, AT&T, Verizon, China Telecom, NTT) have the best — they are home users by definition. Mobile ASNs (T-Mobile, Verizon Wireless, China Mobile) rank second, because Carrier-Grade NAT means each IP represents thousands of real subscribers, making false positives expensive. Exceptions: hosting providers that resell to legitimate businesses (often get a pass), and residential ISPs compromised at scale (often downgraded).
Look up an IP's ASN reputation with: ipinfo.io (clean UI, free tier, returns org/ASN/country/abuse contact), ip-api.com (free for non-commercial use, returns ASN plus mobile/carrier/hosting flags), BGP.tools or bgp.he.net (raw BGP data, good for understanding the routing path), and PeeringDB (operator-level data, useful for understanding network relationships). IPCombo's per-target real IP column shows the ASN alongside the IP — so you can spot at a glance if a target is hitting a blocked cloud range versus a trusted residential one.