What exactly is an ASN and why does it matter?

An ASN is a unique number assigned to a network that advertises routes on the internet; knowing it reveals who operates the address space and helps with routing, security, and diagnostics.

Does the tool work for both IPv4 and IPv6 addresses?

Yes, you can paste either format and the tool will map it to the most specific announced prefix and the originating autonomous system.

What information will I see after I run a lookup?

You will typically see the ASN, the AS name, the most specific announced prefix, the associated organization or ISP, and the Regional Internet Registry that allocated the block.

Why does my result show a “most specific” prefix?

It indicates the smallest routed block covering the IP, which is often the most accurate view of who originates traffic to that address.

Can different tools show different ASNs for the same IP?

Yes, BGP is distributed and views vary; MOAS events and timing differences can lead to different origin AS observations across vantage points.

Why do I see “private” or “reserved” instead of an ASN?

Private, reserved, and carrier-grade NAT ranges are not globally routed, so they do not have a public originating ASN.

Does running a lookup store my IP or query history?

The tool is designed to be privacy-conscious and to limit retention; it returns routing context without revealing personal identities.

Is the AS name always the same as the company brand I recognize?

Not necessarily; registry names can reflect legal entities or legacy labels, while operations or branding may have changed over time.

How often should I re-check an IP during an incident?

During active events, re-run lookups periodically because route origins and specificity can change as networks mitigate or reroute traffic.

Can I use the results to create access rules or filters?

Yes, many teams key policies on ASNs or prefixes; validate carefully, monitor for changes, and review exceptions to avoid unintended blocking.

ASN Lookup - IP to ASN, ISP, RIR, Prefix & Country

ASN Lookup Tool: Identify the Network Behind Any IP

Every public IP address on the internet is announced by a network that follows a unified routing policy known as an Autonomous System (AS). That network is identified by an Autonomous System Number (ASN), and learning it instantly tells you which organization is responsible for routing that address space. Our ASN lookup tool makes that discovery quick and reliable, revealing operator details, the most specific prefix being announced, and registry context that explains where a block originated. It works for both IPv4 and IPv6 and is built to be fast, simple, and privacy-conscious for everyday troubleshooting.

When you open the page, we automatically detect your current IP and show its ASN details so you can see a live example without typing anything. You can also paste any valid address to run an on-demand check. With IP address ASN lookup, you can move from an opaque IP string to a human-readable network identity in a single step, which is invaluable for routing diagnostics, abuse handling, threat investigations, and performance testing.

Understanding ASN Lookup

An AS is essentially a network under one administrative domain that advertises routes to the broader internet using the Border Gateway Protocol (BGP). ASNs are unique integers (for example, AS64500) that let routers make high-level decisions about where to forward traffic. An IP to ASN lookup maps a specific address to the smallest announced prefix covering it, then to the AS that originates or most specifically announces that prefix. From there, the tool presents the network’s descriptive name and the allocation context (such as the Regional Internet Registry that issued the block: ARIN, RIPE NCC, APNIC, LACNIC, or AFRINIC).

How ASN Lookup Works

Under the hood, the tool compares the queried IP against curated route tables and registry datasets. For IPv4, that means testing the address against a trie of announced prefixes from /0 down to the most specific boundary (often /24, but sometimes longer); for IPv6, it checks from /0 down to a typical floor like /48 or /64. An IP to ASN lookup then binds the best match to the originating AS and enriches that with metadata—name, type, and registry attribution—so you get a narrative answer rather than a cryptic number.

What Results You’ll See

Paste any address and you’ll typically get:

ASN: the numeric identifier (e.g., AS64500).
AS Name: the organization that operates the autonomous system.
Most Specific Announced Prefix: the exact routed range covering the IP.
Registry Attribution: the RIR that allocated the block (ARIN, RIPE NCC, APNIC, LACNIC, or AFRINIC).
High-Level Organization or ISP: the entity commonly associated with the range.

In many cases you will also see whether the prefix is unusually specific, which can hint at traffic engineering, multi-homing, or recent routing changes. The ASN lookup tool presents this context in plain language so you can form a quick hypothesis and continue your investigation with confidence.

Why ASN Data Matters

Knowing the ASN behind an IP turns guesswork into a directed workflow. For incident response, you can identify the network of origin, look for patterns in event logs by AS, and prioritize engagements when a spike maps to a small number of autonomous systems. For performance engineering, ASN context explains why certain routes perform better—peering and transit relationships are reflected in how prefixes are originated and propagated.

ASN information also aids compliance and access decisions. Enterprises often write policies keyed on ASNs when geography alone is too coarse. For example, you might allow traffic from known educational or research networks while applying extra scrutiny to dynamically assigned ranges from consumer ISPs. With IP address ASN lookup readily available, these controls can be maintained with less friction.

Use Cases Across Teams

Diverse teams benefit from the same core capability:

Security Operations: triage malicious connections by grouping indicators under their originating AS and routing footprint.
Network Engineering: validate whether upstream announcements match design intent and detect unexpected origin changes.
Abuse Handling: identify the responsible network to send actionable reports with the right evidence.
Site Reliability: correlate latency or packet loss with specific autonomous systems and prefixes during incident reviews.
Support & QA: answer customer questions about reachability and path asymmetry with authoritative routing context.

IPv4 and IPv6 Nuances

While the lookup experience is the same, IPv6 introduces much larger address space and different operational conventions. You may see longer or shorter prefixes depending on allocation strategy and address planning within an organization. Some networks announce both IPv4 and IPv6 for the same service; mapping both can reveal differing paths or performance characteristics. Our interface treats them consistently so you can compare outcomes side by side.

Accuracy, Data Sources, and Limits

Results reflect a synthesis of live and historical routing data as well as registry information. Keep in mind that BGP is a distributed system, and the “view” of routes can vary by vantage point. Multi-Origin AS (MOAS) situations—where the same prefix appears to originate from multiple ASNs—can occur, and most specific announcements may change during outages or maintenance. In private networks, carrier-grade NAT, or reserved address ranges, you may not receive a public ASN because those addresses are not globally routed.

Registry metadata is authoritative about allocation but does not guarantee operational ownership today. Organizations merge, rebrand, or reassign blocks. That is why the tool focuses on the most specific active announcement and pairs it with registry context to tell the full story.

Privacy and Security Considerations

The tool is designed to minimize data retention and avoid exposing sensitive information. Looking up an address reveals routing and registry context, not customer identities or end-user details. Always handle results responsibly and follow legal and organizational policies when using ASN data for enforcement or filtering.

Tips for Interpreting Results

Consider these guidelines as you analyze outputs:

Prefer the most specific announced prefix when assessing who currently steers traffic to an IP.
Use RIR attribution as historical context, not definitive proof of present-day operations.
Watch for MOAS entries or sudden origin changes; both can signal misconfiguration or hijacking.
Compare IPv4 and IPv6 outcomes; divergent paths sometimes explain performance outliers.
Re-check critical addresses during incidents because routing states can shift rapidly.

Getting Started in Seconds

Open the page and you’ll see a live readout for your current IP. Paste any other address to run a fresh check, then copy the results into tickets, runbooks, or dashboards. Whether you are documenting a peering change, answering a support case, or prioritizing an investigation, the ASN lookup tool gives you a concise, dependable snapshot of network ownership and routing scope so you can act with clarity.

ASN Lookup