IP to ASN Lookup
Query an IP address to get the ASN, or enter an AS to get the details and IP ranges assigned to the block.
IP address to Autonomous System (ASN)
When using IP to ASN enter an IP address or a list of IP addresses. The results will be a comma separated list of ASN’s with details.
An autonomous system is a collection of IP routing prefixes. The AS numbers and associated BGP routing is what makes the Internet work. It is how your packet gets from your local ISP to Google, Amazon or the cat videos hosted on the other side of the world.
ASN Details
Entering an AS will perform a query that retrieves the details of the AS organisation and the IP address prefixes that have been assigned to the network. For example Google has an AS number 15169, enter this as AS15169.
Performing Bulk IP address Lookups
Over at HackerTarget.com there is an AS Lookup tool that allows bulk lookups of thousands of IP addresses at a time. Results can be easily exported to XLSX or CSV.
List of ASN by IP count (top 20 ASNs)
An examination of the largest AS blocks using IPv4 count as the metric for size of the block.
There is an interesting difference between these organisations and networks; some are clearly Internet Service Providers and Telecommunication companies while others are hosting companies that are supplying services from the IP space.
| IPv4 Count | ASN | Name |
|---|---|---|
| 116015278 | 4134 | CHINANET-BACKBONE No.31,Jin-rong Street, CN |
| 115915094 | 7018 | ATT-INTERNET4, US |
| 75053774 | 721 | DNIC-ASBLK-00721-00726, US |
| 71428718 | 7922 | COMCAST-7922, US |
| 70406374 | 17676 | GIGAINFRA Softbank BB Corp., JP |
| 68252402 | 4766 | KIXS-AS-KR Korea Telecom, KR |
| 58710480 | 3356 | LEVEL3, US |
| 58665000 | 4837 | CHINA169-BACKBONE CHINA UNICOM China169 Backbone, CN |
| 58156438 | 8003 | GRS-DOD, US |
| 57982692 | 9808 | CMNET-GD Guangdong Mobile Communication Co.Ltd., CN |
| 46906118 | 714 | APPLE-ENGINEERING, US |
| 44308754 | 701 | UUNET, US |
| 43380522 | 9394 | CTTNET China TieTong Telecommunications Corporation, CN |
| 38437444 | 8075 | MICROSOFT-CORP-MSN-AS-BLOCK, US |
| 38267080 | 16509 | AMAZON-02, US |
| 36033366 | 3320 | DTAG Internet service provider operations, DE |
| 35122774 | 6167 | CELLCO-PART, US |
| 29782364 | 4538 | ERX-CERNET-BKB China Education and Research Network Center, CN |
| 29643556 | 174 | COGENT-174, US |
| 28973378 | 4713 | OCN NTT Communications Corporation, JP |
