Autonomous systems
Every public address belongs to one autonomous system. The index on this server knows 82,135 of them; this directory lists the largest by the number of prefixes they hold, with the operator, the registry that allocated the system and what the lists say about it.
The largest networks
Ranked by the prefixes the ASN database assigns to each system, both address families together. Each page lists the prefixes, the registry facts and the operator-level flags, and the same facts are one API call away.
| asn | operator | ipv4 prefixes | ipv6 prefixes | registry |
|---|---|---|---|---|
| AS20940 | Akamai International B.V. | 3,847 | 8,065 | ripencc |
| AS4134 | Chinanet | 9,217 | 1,686 | apnic |
| AS174 | Cogent Communications | 8,780 | 541 | arin |
| AS7018 | AT&T Enterprises, LLC | 7,670 | 214 | arin |
| AS16509 | Amazon.com, Inc. | 5,977 | 1,366 | arin |
| AS4766 | Korea Telecom | 5,410 | 7 | apnic |
| AS721 | DoD Network Information Center | 5,292 | 19 | arin |
| AS9808 | China Mobile Communications Group Co., Ltd | 2,777 | 2,438 | apnic |
| AS701 | Verizon Business | 4,587 | 212 | arin |
| AS45609 | Bharti Airtel Limited | 343 | 4,418 | apnic |
| AS3356 | Level 3 Communications, Inc. | 4,355 | 152 | arin |
| AS209 | CenturyLink Communications, LLC | 4,397 | 67 | arin |
| AS7922 | Comcast Cable Communications, LLC | 2,702 | 1,636 | arin |
| AS9121 | Turk Telekomunikasyon Anonim Sirketi | 747 | 3,475 | ripencc |
| AS47331 | TTNet A.S. | 154 | 3,593 | ripencc |
| AS3257 | GTT Communications Inc. | 3,592 | 101 | ripencc |
| AS3549 | Level 3 Communications, Inc. | 3,203 | 122 | arin |
| AS9009 | M247 Europe SRL | 2,682 | 226 | ripencc |
| AS212238 | Datacamp Limited | 2,723 | 168 | ripencc |
| AS749 | United States Department of Defense (DoD) | 2,809 | 0 | arin |
| AS3786 | LG DACOM Corporation | 2,776 | 6 | apnic |
| AS9318 | SK Broadband Co Ltd | 2,588 | 3 | apnic |
| AS7545 | TPG Internet Pty Ltd | 1,941 | 574 | apnic |
| AS24560 | Bharti Airtel Limited | 891 | 1,424 | apnic |
| AS13335 | Cloudflare, Inc. | 927 | 1,333 | arin |
| AS22394 | Verizon Business | 358 | 1,759 | arin |
| AS4837 | CHINA UNICOM China169 Backbone | 1,377 | 724 | apnic |
| AS2914 | NTT America, Inc. | 1,923 | 123 | arin |
| AS56040 | China Mobile Communications Corporation | 762 | 1,190 | apnic |
| AS140292 | China Telecom | 1,925 | 1 | apnic |
| AS38266 | Vodafone Idea Ltd. (VIL) | 80 | 1,820 | apnic |
| AS45271 | Vodafone Idea Ltd. (VIL) | 150 | 1,682 | apnic |
| AS36183 | Akamai Technologies, Inc. | 231 | 1,581 | arin |
| AS10620 | Telmex Colombia S.A. | 1,120 | 687 | lacnic |
| AS14080 | Telmex Colombia S.A. | 379 | 1,241 | lacnic |
| AS6167 | Verizon Business | 557 | 1,038 | arin |
| AS39386 | Saudi Telecom Company JSC | 18 | 1,576 | ripencc |
| AS22773 | Cox Communications Inc. | 1,528 | 49 | arin |
| AS16625 | Akamai Technologies, Inc. | 1,522 | 1 | arin |
| AS6079 | RCN | 1,394 | 96 | arin |
| AS7029 | Windstream Communications LLC | 1,401 | 58 | arin |
| AS31898 | Oracle Corporation | 1,191 | 262 | arin |
| AS14618 | Amazon.com, Inc. | 1,085 | 305 | arin |
| AS8075 | Microsoft Corporation | 1,148 | 172 | arin |
| AS20115 | Charter Communications | 984 | 332 | arin |
| AS12389 | PJSC Rostelecom | 1,266 | 46 | ripencc |
| AS17072 | TOTAL PLAY TELECOMUNICACIONES, S.A.P.I. DE C.V. | 205 | 1,075 | lacnic |
| AS2764 | AAPT Limited | 1,250 | 21 | apnic |
| AS26599 | TELEFÔNICA BRASIL S.A | 180 | 1,070 | lacnic |
| AS9304 | HGC Global Communications Limited | 1,151 | 71 | apnic |
| AS6461 | Zayo Bandwidth | 1,141 | 69 | arin |
| AS39891 | Saudi Telecom Company JSC | 73 | 1,130 | ripencc |
| AS36352 | HostPapa | 1,175 | 17 | arin |
| AS3561 | CenturyLink Communications, LLC | 1,155 | 0 | arin |
| AS17816 | China Unicom IP network China169 Guangdong province | 517 | 636 | apnic |
| AS8151 | Uninet S.A. de C.V. | 919 | 224 | lacnic |
| AS55410 | Vodafone Idea Ltd. (VIL) | 127 | 1,004 | apnic |
| AS2828 | Verizon Business | 1,122 | 1 | arin |
| AS11492 | CABLE ONE, INC. | 1,120 | 1 | arin |
| AS15830 | Equinix (EMEA) Acquisition Enterprises B.V. | 829 | 291 | ripencc |
| AS25019 | Saudi Telecom Company JSC | 233 | 853 | ripencc |
| AS5650 | Verizon Business | 1,035 | 34 | arin |
| AS27947 | Telconet S.A | 112 | 875 | lacnic |
| AS27986 | ENTEL CHILE S.A. | 5 | 982 | lacnic |
| AS702 | Verizon Business | 895 | 67 | arin |
| AS44559 | IT HOSTLINE LTD | 959 | 1 | ripencc |
| AS30036 | Mediacom Communications Corp | 553 | 396 | arin |
| AS577 | Bell Canada | 905 | 36 | arin |
| AS21859 | Zenlayer Inc | 844 | 95 | arin |
| AS852 | TELUS Communications Inc. | 854 | 73 | arin |
| AS13999 | Mega Cable, S.A. de C.V. | 594 | 333 | lacnic |
| AS20473 | The Constant Company, LLC | 693 | 187 | arin |
| AS203020 | HostRoyale Technologies Pvt Ltd | 813 | 53 | ripencc |
| AS62240 | Clouvider Limited | 776 | 82 | ripencc |
| AS3320 | Deutsche Telekom AG | 815 | 39 | ripencc |
| AS34984 | Superonline Iletisim Hizmetleri A.S. | 683 | 136 | ripencc |
| AS4808 | China Unicom Beijing Province Network | 719 | 98 | apnic |
| AS29802 | HIVELOCITY, Inc. | 704 | 110 | arin |
| AS7377 | University of California, San Diego | 790 | 2 | arin |
| AS27064 | DoD Network Information Center | 778 | 0 | arin |
| AS10753 | Level 3 Communications, Inc. | 714 | 13 | arin |
| AS9498 | Bharti Airtel Limited | 664 | 60 | apnic |
| AS6939 | Hurricane Electric LLC | 505 | 201 | arin |
| AS9829 | Bharat Sanchar Nigam Ltd | 293 | 405 | apnic |
| AS5511 | Orange S.A. | 683 | 8 | ripencc |
| AS396982 | Google LLC | 628 | 55 | arin |
| AS9583 | Sify Limited | 661 | 1 | apnic |
| AS10796 | Charter Communications Inc | 621 | 39 | arin |
| AS18779 | EGIHosting | 647 | 8 | arin |
| AS4538 | China Education and Research Network Center | 470 | 182 | apnic |
| AS11404 | Wave Broadband | 607 | 24 | arin |
| AS396356 | Latitude.sh | 597 | 32 | arin |
| AS16276 | OVH SAS | 618 | 9 | ripencc |
| AS3215 | Orange S.A. | 532 | 92 | ripencc |
| AS20001 | Charter Communications Inc | 554 | 62 | arin |
| AS1540 | Headquarters, USAISC | 612 | 0 | arin |
| AS8717 | A1 Bulgaria EAD | 373 | 238 | ripencc |
| AS37518 | Fiber Grid INC | 584 | 0 | afrinic |
| AS6389 | AT&T Enterprises, LLC | 581 | 0 | arin |
| AS4812 | China Telecom (Group) | 517 | 60 | apnic |
catalog warmed 2026-10-02 · index built 2026-10-02
What an autonomous system tells you
An autonomous system number names the network an address is announced from, and the operator behind it is the most reliable fact about an address there is: a cloud, a carrier, a university or a hosting company each announce their own space. The IP lookup answers the number and the operator on every address; these pages turn that around and show every prefix a system holds, the registry that allocated it and when, and whether its operator is on Spamhaus ASN-DROP or a listed satellite or mobile network.
What none of this says is who is using an address today. A prefix belongs to its operator; a person behind a carrier gateway, a VPN exit or a corporate proxy is not the operator. Look up an address to see the flags that separate the two.
Common questions
- What is an autonomous system number?
- An ASN identifies one network that announces its own routes to the Internet under a single routing policy: a cloud, a carrier, a university, a hosting company. Every public IP address belongs to exactly one, which is why the number and the operator behind it are the first facts an IP lookup answers. The glossary entry explains how the number is read.
- Why only the largest networks?
- The index knows every system the ASN database assigns a prefix to, tens of thousands of them, and a page exists for each — but only the largest by prefix count are listed here and submitted for indexing. A network with one /24 does not need a search result; a link to its page still works.
- Where do the prefixes come from?
- From the free DB-IP ASN database turned inside out: the same file the lookup reads address by address is walked once a month to list every prefix per system. The registry, country and allocation date come from the regional registries’ own daily statistics, and the blocklist, satellite and mobile flags from the lists the lookup already uses. Nothing here is a live route table.
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