ASN Lookup: Company Details, BGP Peering, and IP Range Mapping
Perform an advanced ASN lookup to instantly retrieve crucial network data. Our free tool provides full Company Details, comprehensive BGP Peering status, and detailed IP Range Mapping for any Autonomous System Number. Easily perform an AS owner search or ASN lookup by company name to begin your network analysis now.
Comprehensive Company Details and ASN WHOIS Data
Every Autonomous System is tied to a specific organization. Our service provides a deep dive into the ASN WHOIS lookup record, revealing the essential Company Details and ownership information. Quickly perform an ASN lookup by organization name or number to find the registered AS owner, contact emails (administrative, technical, and abuse), and the official registration dates. Use this feature for quick competitive analysis or ownership verification.
Advanced BGP Peering and Routing Analysis
Go beyond basic connectivity with our advanced BGP ASN lookup functionality. We display the current BGP Peering relationships, including upstream and downstream neighbors, allowing you to trace traffic paths accurately. View all publicly advertised IP prefixes (CIDR blocks) associated with the Autonomous System. This real-time routing analysis is essential for network engineers managing performance and security.
IP Range Mapping and Network Geolocation
Instantly visualize the global reach of any network. Our IP Range Mapping feature plots all associated IP prefixes onto a geographical map, providing a visual representation of the ASN location. This unique service simplifies network tracing and confirms the Network Geolocation of the Autonomous System's assets worldwide. This is perfect for quick visual confirmation during fraud or security investigations.
What is an Autonomous System Number (ASN)?
The Internet is built from thousands of smaller, independent networks called Autonomous Systems (AS). An Autonomous System (AS) is a collection of IP networks and routers controlled by a single entity (like a corporation, university, or government agency) that presents a common routing policy to the Internet. Think of an AS as a neighborhood in a city: it has its own internal IP addresses and routers managed by a single entity (like an ISP or a large company). The 'autonomous' part means the organization has full control over its internal traffic routing. The Autonomous System Number (ASN) is a globally unique identifier assigned to that AS. The ASN is essential for the exchange of routing information between different networks.
An autonomous system doesn't just have a number. It also controls actual IP addresses that devices use to communicate. These IP addresses come in organized blocks called prefixes. A prefix like 203.0.113.0/24 contains 256 individual IP addresses. The organization running that AS decides how to use them. Some addresses run their network infrastructure. Others get distributed to customers. Some stay available for expansion. Large networks typically manage dozens or even hundreds of different prefixes. They accumulate these blocks over time through new allocations, company acquisitions, or geographic expansion. Our tool displays all the prefixes an AS currently announces, giving you a complete picture of their IP address holdings and network size.
ASN Format and Structure
Originally, ASNs were 16-bit numbers (ranging from 1 to 65535). Due to the rapid growth of the internet, ASNs are now primarily 32-bit numbers (ranging up to 4,294,967,295). While some private or reserved ranges exist, a publicly routable ASN is required to participate in global routing. Our tool displays the full 32-bit format where applicable.
The Role of BGP (Border Gateway Protocol) in ASN
BGP is the routing protocol that holds the entire internet together. Think of it as the postal system of the internet. Just like post offices need to know how to route mail between cities, BGP helps routers know how to send data between different networks.
The Border Gateway Protocol (BGP) is the internet's core routing protocol. ASNs are the fundamental units BGP uses to exchange data. BGP routers use the ASN to determine the most efficient AS Path for routing traffic. When you perform an ASN lookup, you are essentially querying this BGP routing database to understand the network’s advertised routes.
How BGP Uses ASNs for Internet Routing
When you send data across the internet, it doesn't go directly to its destination. It hops through multiple networks (multiple ASes) to get there. BGP (Border Gateway Protocol) is the system that makes this work. Think of it as the GPS of the internet, finding paths between autonomous systems.
Each AS uses BGP to announce which IP addresses it can reach. Those neighbors pass that information along, and so on. When your data needs to reach a specific IP, routers use this BGP information to figure out which path of ASes will get it there. The route your data takes is called the AS path.
BGP routing decisions consider business relationships, network performance, and policies set by each AS, not just the shortest path. This is why understanding ASN relationships matters for anyone working with network infrastructure.
Types of Autonomous Systems
Not all autonomous systems are created equal. There are different types of AS based on how they connect to the internet:
- Stub AS: A stub AS has only one connection to the internet through a single upstream provider. Most small businesses and organizations fall into this category. They depend entirely on their ISP for internet connectivity. If that connection goes down, they're offline.
- Multihomed AS: A multihomed AS connects to the internet through multiple providers for redundancy. If one connection fails, traffic can flow through another. This is common for medium to large organizations that can't afford downtime. They pay multiple ISPs but don't carry transit traffic for others.
- Transit AS: A transit AS not only connects to the internet but also carries traffic between other networks. These are your ISPs and backbone providers. They have customers who depend on them for connectivity and often have peering relationships with other transit providers.
FAQs
ASNs are publicly listed in regional internet registries. If you know an organization's or company’s name, you can search registries like ARIN, RIPE, or APNIC to find their AS number. Once you have it, just enter it in our lookup tool to see all the details. ASNs are usually written as "AS" followed by numbers (like AS15169), but you can search with just the number in our tool.
Our ASN Lookup tool requires the AS number. If you have an IP address and need to find which ASN it belongs to, use our IP Location API to search up its details and find out its ASN information.
Our tool shows you the company/organization that owns the AS number, all IPv4 and IPv6 address ranges they control, which networks they're connected to for exchanging traffic, registration details from internet registries like ARIN or APNIC, and the country where the ASN is registered. You also get a map view showing where the network's IP addresses are geographically located.
IPv4 prefixes are traditional address blocks (like 192.0.2.0/24), while IPv6 prefixes use the newer address format (like 2001:db8::/32). Both show the IP ranges controlled and announced by the ASN via BGP.