ASN (Autonomous System Number)
A unique number identifying a network operator that controls a block of IP addresses on the internet.
An ASN, or Autonomous System Number, uniquely identifies a network - a collection of IP ranges under the control of a single operator, such as an ISP, mobile carrier, cloud provider, or large company. Every public IP address belongs to an ASN, and anyone can look up which one via public registries.
ASN is the single most important signal in proxy detection. When a site receives a request, it looks up the source IP's ASN to learn who owns that network. An ASN belonging to Comcast, BT, or Vodafone signals a residential or mobile user; an ASN belonging to AWS, Google Cloud, OVH, or Hetzner signals a datacenter - a likely source of automation.
This is exactly why residential proxies work and datacenter proxies get blocked on protected sites. Both hide your real IP, but the ASN lookup exposes the proxy's nature: a residential proxy resolves to a trusted ISP ASN, while a datacenter proxy resolves to a hosting ASN that many sites block by default, regardless of anonymity level.
When you check a proxy, the ASN and organization behind its exit IP tell you how the target will perceive it. A residential ISP ASN means high trust; a hosting-provider ASN means the IP is easily identified as a datacenter proxy. Our proxy checker reports the ASN so you can judge an IP's trust before relying on it.
The number behind every address block
The internet is a network of networks, and each independently routed network is an autonomous system with a number. Amazon has one, your home provider has one, a mobile carrier has one. Address blocks are registered to these numbers, and the registration is public.
That makes classification trivial for anyone who wants it. Take an address, look up its ASN, look up who owns that ASN, and you know within a millisecond whether the traffic comes from a hosting company, a consumer provider or a mobile carrier. No analysis, no machine learning, one database lookup.
This is the first filter almost every anti-bot system applies, and it explains the entire price structure of the proxy market. Hosting ASNs are cheap and widely distrusted. Consumer ASNs are expensive and widely trusted. Carrier ASNs are the most expensive and the most trusted, because banning them hurts real subscribers.
It also explains why ISP proxies exist as a category. They live in a datacenter but their addresses are registered under a consumer provider's ASN, so the lookup returns the answer a site rewards rather than the one it punishes.
How our types look up
Each product answers the ASN question differently, and that answer is most of what you are buying:
What the lookup returns
Datacenter IPv4/IPv6 -> hosting ASN, blocked by sites that filter on it
ISP proxies -> consumer provider ASN, datacenter uptime
Residential -> consumer provider ASN, real household device
Mobile -> carrier ASN, shared with real subscribers
# Check any address yourself:
curl -x login_c_US:password@proxy.sotaproxy.com:10000 https://ipinfo.io/json- Run that check before you conclude a proxy type does not work. The response shows the ASN and the organisation, which tells you exactly what your target sees.
- If a site blocks hosting ASNs, no amount of retrying, header tuning or user-agent editing will help. Change the type.
- ASN reputation is collective. Your dedicated address inherits how the rest of that network behaves, which is part of why datacenter is cheap.
- For account work, matching the ASN class to the story matters: a mobile app account that has only ever logged in from carrier ranges looks wrong arriving from hosting space.
Misconceptions about ASNs
ASN is not geography
A network registered in one country routes traffic in many. Country targeting and ASN class are separate questions.
A clean ASN does not mean a clean address
Reputation exists at both levels. A consumer ASN with a burnt individual address still gets you blocked.
Changing address inside one ASN rarely helps
If the block is at network level, the neighbouring address is in the same network. Move to a different class instead.
ASN checks are not advanced detection
They are the cheapest check available and usually the first. Getting past them is the beginning of the problem, not the end.
See this in practice
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