How to judge the IP class (datacenter / residential / mobile) and read the ASN

ASN stands for Autonomous System Number. It identifies the organization that owns a block of IP addresses. Every time your traffic traverses the Internet, the routing decisions are made between ASNs — 'this IP block is owned by ASN X, which peers with ASN Y, which peers with ASN Z'. The ASN is the stable identifier; IP blocks can be sold or transferred, but the ASN registry is the source of truth.

There are five regional Internet registries (RIRs) that hand out ASNs: ARIN (North America), RIPE (Europe / Middle East), APNIC (Asia-Pacific), LACNIC (Latin America), AfriNIC (Africa). Looking up an ASN tells you which RIR assigned it, which tells you roughly which region the organization operates in.

Datacenter IPs come from cloud providers — AWS, GCP, Azure, Vultr, Linode, DigitalOcean. The ASN registry lists them with names like 'AMAZON', 'GOOGLE', 'MICROSOFT', 'LINODE', 'DIGITALOCEAN'. Look at the ASN orgName and you'll know immediately.

Residential IPs belong to ISPs that allocate addresses to home subscribers. ASN orgNames like 'COMCAST', 'AT&T', 'CHINANET', 'KDDI', 'HKT', 'TELEFONICA' are residential. The IP block is allocated to the ISP; individual subscribers get addresses within that block.

Mobile IPs belong to mobile carriers — T-Mobile, Verizon Wireless, China Mobile, NTT DoCoMo. The ASN orgName will have 'MOBILE' or the carrier name. These IPs rotate among millions of subscribers and are rarely blacklisted because a false-positive would impact millions of real users.

Three reliable methods. (1) whois command line: whois 203.0.113.42 returns the IP block, the org name, and the ASN. (2) IPCombo's per-target IP column shows the ASN inline next to each exit IP — no extra tool needed. (3) ipinfo.io and similar free APIs accept an IP and return ASN info; some have free tiers that suffice for personal use.

When reading whois output, the fields to focus on are: orgName (or OrgName), ASN (or origin), NetType (which can hint at allocation type), and the country code. The ASN registry is updated weekly, so an IP that was residential last year could be sold to a datacenter this year. Always check current data.

ASN is the source of truth, but two corroborating signals catch fakes. Latency: datacenter IPs respond to nearby probes in single-digit ms because the network is in a tightly-controlled datacenter. Residential IPs respond in 20-80ms because the last-mile ISP adds real network distance. Mobile IPs respond in 50-200ms because carrier networks have more hops.

IP block pattern: datacenter IPs are dense — a contiguous /16 allocated within a few years and assigned to many customers. Residential IPs are sparse within a larger ISP block, allocated to individual subscribers over time. Mobile IPs sit in a few /16s per carrier, used by millions of subscribers. The shape of the address space tells you the class even when the orgName is generic.

If the ASN says residential but the latency is 5ms to a target across the world, the residential claim is false — it's a datacenter disguised with a residential label. IPCombo's per-target latency column cross-references the ASN, so disagreement surfaces immediately.

For each service you care about, identify the class it requires. AI tools (ChatGPT, Claude, Gemini) want residential in US/JP/KR/SG, mobile if you can swing it. Streaming (Netflix, Disney+, HBO) wants residential in the catalog region — datacenter is universally blocked. Banking apps want mobile. General browsing works fine on datacenter.

If you're picking a proxy provider, run IPCombo with their exit as your proxy. Look at the per-target real IP column. If the IPs for the services you care about are all in the recommended class and region, you have found your match. If not, no amount of dashboard polish will fix it.