AS81
NCREN

AS81 announces 1,957,376 IPv4 addresses across 69 routed ranges, registered in US. Figures come from the public global routing table and are refreshed daily.

Is AS81 datacenter space?

Not according to the nine cloud and CDN providers whose published range lists we track. That is a statement about those specific lists, not proof the space is residential — plenty of hosting companies never publish machine-readable ranges, and this AS may well be one of them.

The reliable way to classify a specific address is to check it directly rather than to infer from the AS. The free lookup tool checks any address against the Tor exit list and the published cloud-provider ranges. VPN and proxy verdicts need a live visit: they come from a /v1/evaluate call with the browser token, not from a bare address.

What an AS number does and does not tell you

An autonomous system number identifies who announces a block of addresses to the internet's routing table. It is an organisational fact, and a durable one — useful for attributing traffic to a hosting company, a carrier, or a university.

It is not a risk signal. A residential ISP's AS carries the household traffic of millions of ordinary customers and, at the same time, whatever residential proxy exits have been installed on those customers' devices. A hosting AS carries scrapers and legitimate server-to-server integrations in the same ranges. Scoring an address on the reputation of its AS produces exactly the false positives that make fraud tooling untrustworthy.

Announced IPv4 ranges

All 69 announced ranges.

Check a specific address

The AS tells you who announces a range. An address check answers whether one address inside it is a Tor exit or sits in a published cloud range — for example 128.109.0.0, the first address in this AS's announced space; whether a visitor is on a VPN or proxy needs a live visit. The free lookup tool takes any address, and the IP intelligence hub explains what each signal means.

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