ASN Lookup
Operator, prefixes, peers for an AS number or IP.
AS209150 — POINTER TH.PAPAMICHAIL VAINAS - G.PSALTAKIS G.P
- Status
- 1
- Type
- as
- RIR allocation
- 208284-209307
Announced prefixes (first 60)
About ASN Lookup
This tool takes either an Autonomous System Number (such as AS13335 for Cloudflare) or any IP address and returns the operator details, the regional internet registry allocation, and the list of announced prefixes. When you supply an IP, it first looks up which AS announces that prefix, then fetches the AS details. Data comes from RIPE NCC's stat API, which aggregates BGP routing data from public route servers worldwide.
When to use it
Use this to identify which network operator runs a given IP, useful for incident response or just curiosity about who hosts what. Network engineers use it to look up peering candidates and confirm prefix counts. Web hosting evaluations include checking the provider's ASN to see how large their address space is and how stable their announcements are.
How to read the results
The operator (called holder in RIPE responses) is the registered owner. Announced prefixes show every IP range that ASN currently advertises to the internet. A large prefix count (hundreds or thousands of /24s) usually indicates a large ISP or cloud provider. Small counts (a single /22 or two) point at smaller hosts. The RIR allocation block tells you when and from which registry the AS was assigned.
Frequently asked questions
What is an Autonomous System? ▾
An Autonomous System is a network that operates under a single administrative authority and shares a routing policy. Each AS has a unique number used in BGP to announce its IP prefixes to other networks. Every major ISP and cloud provider has at least one ASN.
How does an IP get linked to an ASN? ▾
The AS that operates the IP space announces a prefix containing that IP into BGP. Public route collectors capture these announcements. RIPE stat aggregates them so you can query by IP and find which AS is currently announcing the most specific covering prefix.
Can a single IP belong to two ASNs? ▾
Yes, briefly, during a network migration or in cases of multi-homing. Most of the time, the most-specific announcement wins under longest prefix match. Persistent dual announcements are rare and often indicate a misconfiguration or a BGP hijack.
What does the prefix list tell me? ▾
The prefix list is every IP range the AS currently announces to its peers. Counting them gives a rough sense of network size. Mapping them to geography with the IP info tool helps identify which regions the AS serves.