ASN stands for Autonomous System Number. It is the number that names one network on the internet, such as an internet provider, a cloud or a hosting company. Every address in use on the internet sits in a block that one of these networks announces. Look up any address and you get its ASN and the name of the network's owner. On October 21, 2026, the five regional registries listed 122,930 ASNs in use. Website firewalls can allow, challenge or block visitors by ASN, because it tells a home connection from a rented server. To see the ASN of any address now, use our free IP lookup.
What does ASN mean?
In networking, ASN means Autonomous System Number. RFC 1930 defines an AS as a connected group of IP prefixes with "a SINGLE and CLEARLY DEFINED routing policy". In plain words, an AS is one operator's part of the internet: its address blocks and its rules for routing traffic to them. The ASN is the label on that part. For example, AS7922 belongs to Comcast, AS3320 to Deutsche Telekom and AS14061 to DigitalOcean. AWS lists the usual holders as "internet service providers, enterprises, universities, or government agencies".
ASN
network identifier
A globally unique number for an Autonomous System: one operator's chunk of the internet, the IP blocks it owns and the single policy by which it routes them. The record is public, so anyone can see which network owns an address.
- Also called
- Autonomous System Number
The same three letters mean other things elsewhere. Next to the network meaning, Google suggests "what is an asn advanced shipping notice" and "what is an asn degree in nursing". This page covers the network number only.
How does an ASN work?
Networks tell each other where addresses live through BGP, the Border Gateway Protocol. Each AS announces the address blocks it holds, under its own number, to the networks it connects to. They pass the announcement on, until the whole internet knows which AS should receive traffic for those addresses. Each route also carries its AS path, the list of networks it passed through on the way.
This routing job is what makes the ASN a reliable label. A network needs its number to take part in global routing, and the registry records who holds it. RFC 1930 puts it plainly: "AS number to owner mappings are public knowledge (in WHOIS)".
Who assigns ASNs?
ASNs come down the same chain as IP addresses. In the words of the IANA registry, "IANA allocates AS Numbers to Regional Internet Registries (RIRs)". The registries then "further allocate or assign AS Numbers to network operators in line with RIR policies". There are five of them, each for one part of the world. Their joint statistics file of October 21, 2026, counted the ASNs each had assigned:
| Registry | Region | ASNs in use |
|---|---|---|
| RIPE NCC | Europe, Middle East, Central Asia | 40,050 |
| ARIN | North America | 34,233 |
| APNIC | Asia Pacific | 31,429 |
| LACNIC | Latin America, Caribbean | 14,404 |
| AFRINIC | Africa | 2,814 |
Together that makes 122,930 ASNs. By country, the United States holds 32,270 of them, about a quarter of all. Brazil follows with 9,175, ahead of China, India and Russia.
How many ASNs are there?
The registries counted 122,930 assigned ASNs on October 21, 2026. The space they come from is far larger. The first ASNs were 16-bit numbers, from 0 to 65,535. As that range ran short, RFC 6793 let BGP carry AS numbers "as four-octet entities", which means 32 bits. The numbering now runs to 4,294,967,295.
New networks almost always get a 32-bit number now. Of the 5,384 ASNs the registries' file dates to 2026, 5,225 sit above 65,535, which is 97%. Across everything assigned, the 32-bit numbers have passed half: 66,393 of 122,930, or 54%.
Older BGP routers that only handle 16-bit numbers see AS 23456, called AS_TRANS, in place of a 32-bit number. IANA's registry, last updated June 1, 2026, shows blocks given to the registries up to AS 404,380. Everything from 404,381 to 4,199,999,999 is still unallocated.
What is a private ASN?
A private ASN is a number reserved for use inside a network, never on the public internet. RFC 6996 sets aside 64512 to 65534, which is 1,023 numbers. It adds 4200000000 to 4294967294, which is 94,967,295 more. The RFC names data center networks as one reason the larger range was needed. Before a route goes out to the public internet, private ASNs "MUST be removed" from its AS path.
Two more small ranges, 64496 to 64511 and 65536 to 65551, are kept for documentation and sample code. The sample firewall rule in the AWS documentation uses AS 64496 and AS 64500 from that range.
Does every company have an ASN?
No. RFC 1930 says a site with only one provider needs no AS of its own. Its "prefixes should be placed in an AS of the site's provider". A site that connects to more than one provider is different: "An AS is required". That is why homes and most small businesses have no ASN. A lookup on a home connection names the internet provider, such as Comcast or Deutsche Telekom.
What is the difference between an ASN and an IP address?
An IP address names one endpoint. An ASN names the network that announces whole blocks of addresses, often millions of them. We asked RIPEstat, the public data service of the RIPE NCC, what seven well-known networks announced on October 22, 2026:
| Network | ASN | IPv4 announced |
|---|---|---|
| AT&T | AS7018 | 96.4 million |
| Comcast | AS7922 | 68.2 million |
| Deutsche Telekom | AS3320 | 34.2 million |
| Reliance Jio | AS55836 | 4.2 million |
| DigitalOcean | AS14061 | 3.1 million |
| AS15169 | 2.6 million | |
| M247 | AS9009 | 1.6 million |
Your IP address tells a site roughly where you are. The ASN tells it who runs the network you came from. You can change your apparent location with every proxy you pick. The owner of an address block stays on record at the registry.
How do you look up an ASN?
Three free ways cover almost every case.
One address, in a browser. Our IP lookup shows any address's ASN and operator. It also says whether the address belongs to a datacenter or a home network, and whether it is a known proxy. To test a proxy itself, paste it into our proxy checker. It shows the ASN behind the proxy's IP and whether that network is a datacenter range or a residential one.
Many addresses, from code. Our free IP location and ASN API needs no key. It returns the ASN, its organization and the ISP for any public address:
curl https://hproxy.com/api/ip/YOUR-IP
An AS number, at the registry. RIPEstat returns the holder of any AS number:
curl "https://stat.ripe.net/data/as-overview/data.json?resource=AS7922"
On October 22, 2026, it named "Comcast Cable Communications, LLC" as the holder of AS7922, assigned by ARIN. A WHOIS query at the registry returns the same holder.
Why do websites check your ASN?
A site learns your IP address the moment your connection opens, before your browser sends a single header. One lookup turns the address into an ASN. That makes the network's owner one of the first facts a site has about any visitor.
Firewalls turn that fact into rules. The ASN match rule of AWS WAF lets a site "allow or block traffic from specific network organizations". One rule can list up to 100 ASNs. AWS calls this steadier than rules for single addresses, "as ASNs change less frequently than IP ranges". Cloudflare's IP Access rules come with every plan. They can "allowlist, block, and challenge traffic" by IP address, ASN or country. Cloudflare's rate limiting can also count requests per ASN, so a whole network shares one limit.
Connection opens
your IP is known
ASN lookup
who runs the network
Network type
provider or hosting
Rule
allow, challenge or block
Hosting networks take the hard end of these rules. Few real shoppers browse from a server rack, so a site loses few customers when it blocks a hosting ASN. That goes a long way to explain why a datacenter proxy meets more blocks than a residential proxy. A residential address sits in an internet provider's ASN, among that provider's own subscribers. An ISP proxy works the same way: a fixed address on a home provider's network, run from a server. We compare the types with numbers in datacenter vs residential proxies.
A check by ASN is only the first gate. Cloudflare wrote in 2024: "Advanced bots bypass country blocks, ASN blocks, and rate-limiting". They move into residential address space instead. Its model then found residential proxy activity in more than 45,000 ASNs across 237 countries and regions. Sites therefore stack more signals on top, which how websites detect proxies walks through.
What do free proxies show about ASNs?
Our free proxy list shows how lopsided the networks behind proxies can be. At 08:03 UTC on October 22, 2026, it held 6,990 working free proxies on 1,665 ASNs. One network carried 2,156 of them: M247 (AS9009), a hosting company. That is 31% of the list on a single ASN.
The ten largest networks held 2,782 proxies, 40% of the list. In all, 3,106 proxies (44%) had addresses our checker marks as hosting. For a site, one ASN rule goes a long way: blocking AS9009 alone would turn away almost a third of them. You can browse the working list network by network on our free proxy list by ASN.
Can you choose a proxy by its ASN?
Yes, where a provider sells targeting by network. Some jobs need one operator in particular, such as checking an ad as one provider's subscribers see it. Choosing proxies by ASN and ISP covers four jobs where the operator is the requirement. It also shows how to count the networks a pool really offers.
On our side, Residential Premium takes an asn value with a country, for example 7922 for Comcast or 7018 for AT&T. It costs $1.49 per GB, falling to $1.00 per GB at 1,000 GB+. Both residential plans are on our residential proxies page. Whatever you buy, run a few exit addresses through an IP lookup first: the ASN shows whose network you are really on. Survey work is another job where the network type matters, covered in proxies for surveys.
What this page could not check
- Registry counts move. The ASN counts come from the registries' joint file of October 21, 2026. The file dates 5,384 assignments to 2026 alone, so the totals keep rising.
- One ASN per company. The announced address counts are what RIPEstat saw on October 22, 2026, for one ASN each. Large companies often run several ASNs, so a company's total can be higher.
- Our free list only. The network counts cover only the public free proxies our checker collects, at one moment.
- Firewall settings vary. AWS and Cloudflare document what their rules can do. We cannot see which sites switch them on.
- Check by January 22, 2027. Registry counts and firewall features change.
Sources
- RFC 1930: Guidelines for creation, selection, and registration of an Autonomous System (AS). IETF, March 1996.
- RFC 6793: BGP Support for Four-Octet Autonomous System (AS) Number Space. IETF, December 2012.
- RFC 6996: Autonomous System (AS) Reservation for Private Use. IETF, July 2013.
- Autonomous System (AS) Numbers. IANA registry, last updated June 1, 2026, read October 22, 2026.
- Extended delegated statistics of the five regional registries. Number Resource Organization (NRO), file of October 21, 2026.
- RIPEstat AS overview and routing status for AS7018, AS7922, AS3320, AS55836, AS14061, AS15169 and AS9009. RIPE NCC, read October 22, 2026.
- Autonomous System Number (ASN) match rule statement. AWS WAF Developer Guide, read October 22, 2026.
- IP Access rules, and rate limiting parameters. Cloudflare documentation, read October 22, 2026.
- Machine learning to detect bot attacks through residential proxies (post on bot management model v8). Cloudflare blog, June 24, 2024, updated July 15, 2026.
- HProxy free proxy list, working proxies by network, October 22, 2026, 08:03 UTC.
