What is an ASN and why does it matter?
An ASN (Autonomous System Number) is a unique number assigned to a network, such as an internet provider or a company, that manages its own independent routing on the internet. ipnow.kr shows the ASN and provider name behind your connection right away.
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What exactly does an ASN identify?
An ASN identifies an autonomous system, a block of the internet managed independently by one organization, such as a provider, a cloud company, a university, or a large enterprise.
For example, KT uses AS4766 and SK Broadband uses AS9318, each its own number. If an IP address is like a street address, an ASN is closer to the name of the neighborhood that manages it.
Why is an ASN needed?
The internet is made of countless networks exchanging route information with each other, using a protocol called BGP that announces which IP ranges belong to which ASN. Without ASNs, routers around the world would have no way to find the path to your provider.
In that sense, an ASN acts as part of the addressing backbone that keeps internet traffic from getting lost on its way to a destination.
How do I check my ASN on ipnow.kr?
The ipnow.kr homepage shows your public IP together with the provider name and ASN behind it, no setup required.
From a terminal, curl ipnow.kr/json returns the asn, isp, and as_org fields. If you want to understand the IPv4 and IPv6 relationship too, see IPv4 vs IPv6.
What are some well-known ASNs?
In Korea, major providers include KT (AS4766), SK Broadband (AS9318), and LG Uplus (AS17858, AS3786). Globally, Cloudflare (AS13335) and Google (AS15169) are widely recognized examples.
A single company can run more than one ASN for different services, so treat the ASN as useful context alongside the provider name rather than an absolute identity.
| Item | Value | Source |
|---|---|---|
| Major Korean provider ASNs | KT AS4766, SK Broadband AS9318, LG Uplus AS17858 | DB-IP ASN Lite · 2026-09-24 |
| Global provider ASN examples | Cloudflare AS13335, Google AS15169 | DB-IP ASN Lite · 2026-09-24 |
Frequently asked questions
Who assigns ASN numbers?
Regional internet registries, such as APNIC, working through KRNIC in Korea, assign unique ASN numbers to organizations that apply for one.
Why does the same provider sometimes have more than one ASN?
Mergers or separated business units can leave one company operating several ASNs. LG Uplus using both AS17858 and AS3786 (formerly LG DACOM) is one example.
What is the benefit of knowing my ASN?
It helps when analyzing access logs or filtering bots and abuse, since it tells you which provider or corporate network a connection came from.
Is an ASN permanently tied to an IP range?
No, if a provider reorganizes its IP ranges or transfers them to another company, the ASN information can change. ipnow.kr displays ASN data based on DB-IP.