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ASN Tool

ASN Lookup

Look up ASN, ISP, organization, and country for an IP address.

Find IP Network Owner

Look up ASN, ISP, organization, and country for an IP address.

Knowledge Base

What is an ASN Lookup?

An ASN (Autonomous System Number) is a globally unique identifier assigned to an Autonomous System (AS) by the Internet Assigned Numbers Authority (IANA). An Autonomous System is a massive network or a collection of routers under the control of a single entity—such as an Internet Service Provider (ISP), a tech giant (like Google or Microsoft), a university, or a government agency—that governs its own routing policy.

An ASN Lookup is a specialized network intelligence tool that queries global routing tables and databases (like WHOIS and RADB) in real-time. By inputting an ASN (e.g., AS15169) or an IP address, this tool retrieves comprehensive details about the network's owner, its geographic registry, its IP address blocks (IP prefixes), and upstream peers.

The internet is essentially a network of networks. These massive systems use the Border Gateway Protocol (BGP) to exchange routing information and dynamically decide the most efficient paths to send data packets globally. ASN metadata provides the blueprint of how these massive networks interconnect.

For cybersecurity analysts, network administrators, and threat hunters, performing an ASN query is vital. It helps trace the true network organization hosting malicious actors, identify server locations, map out routing paths, and analyze BGP announcements to ensure clean, unintercepted data delivery.

How to Use It

1

Input ASN or IP

Enter the target Autonomous System Number (e.g., AS3215) or any public IP address you wish to map into the input field above.

2

Run Database Query

Click the lookup button to query global registry authorities (such as ARIN, RIPE, APNIC) and active BGP routing logs.

3

Inspect Network Map

Instantly review registry data, including owner organization name, geographical headquarters, registered IP prefixes, and peer networks.

Administration Tip: Checking an IP's ASN is the most reliable way to detect proxy or VPN hosting. While residential users use standard consumer ISP ASNs, commercial VPN services and data centers use hosting ASNs (like DigitalOcean, Linode, or AWS) which are easily identified and filtered by strict firewalls.

Frequently Asked Questions

Understand BGP routing, Autonomous Systems, RIR registries, and IP address space allocations.

Originally, ASNs were defined as 16-bit integers, allowing for up to 65,536 unique numbers. To accommodate the massive growth of global cloud networks, the Internet Engineering Task Force (IETF) expanded ASNs to 32-bit integers, increasing the pool to over 4 billion unique numbers. Today, 32-bit ASNs are standard and look like any other large number (e.g., AS394123).

Every public IP address belongs to an IP Prefix (a range of IP addresses) owned or managed by an Autonomous System. When you perform an ASN lookup on an IP address, the tool identifies the enclosing IP range and routes you back to the parent Autonomous System Number responsible for directing traffic to that IP block.

RIRs are non-profit organizations that allocate and register IP addresses and ASNs within specific regions of the world. There are five global RIRs: ARIN (North America), RIPE NCC (Europe, Middle East, Central Asia), APNIC (Asia-Pacific), LACNIC (Latin America and Caribbean), and AFRINIC (Africa).

IP Prefixes are blocks of contiguous IP addresses represented in CIDR notation (e.g., 192.0.2.0/24). An Autonomous System advertises these prefixes to the rest of the internet using the Border Gateway Protocol (BGP). This informs other networks that any traffic destined for those IP ranges should be routed to their specific Autonomous System.

No. Only large organizations that route their own traffic via BGP and operate independent network infrastructure need to register an ASN. Small websites, local businesses, and private servers rent IP address space and hosting environments from larger cloud providers (like Amazon Web Services or DigitalOcean) and route traffic using the provider's ASN.

Yes. Network administrators dynamically alter routing configurations to handle outages, optimize speeds, or buy/lease new IP prefixes from other companies. When these changes are executed, BGP announcements update the global routing tables within minutes. Our tool queries live databases to ensure you see the most current network configurations.

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