ASN Lookup - Find Autonomous System Information
Look up any ASN to find network ownership, allocated IP prefixes, routing policies, and peering information. Essential for network operations and research.
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Understanding This Tool
What It Does
Find the Autonomous System Number (ASN) for any IP address and research the organization operating that ASN. ASNs identify major network operators like ISPs, cloud providers, and large tech companies on the internet backbone.
Understanding the Results
- ASN Number: The unique identifier for the autonomous system
- Organization Name: The company operating the ASN
- Country: Primary jurisdiction of the ASN operator
- IP Ranges: All CIDR blocks assigned to this ASN
- Registration Details: When the ASN was registered and by whom
- Preferred Contact: Administrative contact for the ASN
Common Use Cases
- ISP Identification: Determine which provider manages an IP address
- Network Routing: Understand BGP routing and network paths
- Infrastructure Planning: Map out peering relationships and network topology
- Threat Intelligence: Track IP ranges controlled by known bad actors
- Network Forensics: Link multiple IPs to the same network operator
Pro Tips & Best Practices
- AS Numbers: Typically 16-bit (1-65535) or 32-bit (65536+) identifiers
- Major ASNs: Large providers like AWS, Azure, and major ISPs control extensive ranges
- BGP Hijacking: Understanding ASNs helps detect route hijacking attacks
Frequently Asked Questions
An Autonomous System Number (ASN) uniquely identifies a network on the internet. Large organizations, ISPs, and cloud providers have ASNs to manage their routing and interconnections.
Our ASN lookup tool automatically determines the ASN from any IP address by querying global routing databases. You'll see the ASN number, organization name, and country.
ASN data helps identify network ownership, troubleshoot routing issues, implement ASN-based firewall rules, analyze BGP routing, and understand internet topology and peering relationships.
An organization can own IP blocks without an ASN (using provider's routing). Having an ASN means the organization controls its own routing and peering, indicating a larger, more independent network.
Private ASNs (64512-65534, 4200000000-4294967294) are for internal use only and not routed on the public internet, similar to private IP addresses.
Frequently Asked Questions
What is an ASN?
An Autonomous System Number (ASN) uniquely identifies a network on the internet. Large organizations, ISPs, and cloud providers have ASNs to manage their routing and interconnections.
How do I find the ASN for an IP address?
Our ASN lookup tool automatically determines the ASN from any IP address by querying global routing databases. You'll see the ASN number, organization name, and country.
What can I do with ASN information?
ASN data helps identify network ownership, troubleshoot routing issues, implement ASN-based firewall rules, analyze BGP routing, and understand internet topology and peering relationships.
What's the difference between ASN and IP ownership?
An organization can own IP blocks without an ASN (using provider's routing). Having an ASN means the organization controls its own routing and peering, indicating a larger, more independent network.
Are private ASNs valid on the internet?
Private ASNs (64512-65534, 4200000000-4294967294) are for internal use only and not routed on the public internet, similar to private IP addresses.
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How this tool works: This tool runs in your browser and on our server in real time. Depending on the tool, results are computed directly from the input you provide or retrieved from live, authoritative data sources at the moment you run a lookup. We do not sell your data, and your lookups are kept private — any history shown here is stored only on your device.