IP & ASN Lookup
Enter an IP address or a domain to see the network that announces it, its ASN, address range, registry and reverse DNS name.
Questo contenuto è in inglese.
Esempi svolti
Looking up an address
203.0.113.25 typed into the address box
(Illustrative) Network operator: a provider named in the registry record. Autonomous system number AS64500, with the country GB shown for the registered address block.
The result shows who runs the network, not the physical location of a server or person.
Looking up a domain
example.com typed into the domain box
(Illustrative) The address block and autonomous system for the site, plus its name servers and mail servers.
For a domain, the name servers and mail servers are listed alongside the network details.
Informazioni su IP & ASN Lookup
Every public IP address belongs to a network run by an organisation, and each network has an autonomous system number, or ASN. Knowing the ASN tells you who announces the address on the internet, which is useful when you are tracing a hosting provider, reading server logs or deciding who to contact about abuse. This tool shows the ASN, the network name, the announced address range and the registry for any IP address. It is a quick way to turn a bare string of numbers in a log file or an alert into the name of a real organisation you can contact.
Enter an IPv4 or IPv6 address, or a domain name. For a domain we look up its web addresses and also those of its name servers and mail servers, so you can see at a glance whether they share a provider. Each address also gets its reverse DNS name, checked to see whether it matches forwards. Please note that this shows who runs the network, not exactly where a server or a person is. The country is where the address block is registered. The same view works for a single address or for a whole domain, which makes it handy when you are mapping out where a service really runs.
Come usare IP & ASN Lookup
- Enter an IP address or a domain name.
- Select Look up network.
- Read the networks summary to see which providers are involved.
- Check the address table for each address, its role and its reverse DNS name.
- Use the ASN or range when contacting a provider or writing a firewall rule.
Usi comuni
- Finding which hosting provider runs a website
- Working out who to contact about abuse from an address
- Seeing whether web, mail and DNS all depend on one provider
- Understanding unfamiliar addresses in server logs
- Confirming a reverse DNS name matches before setting up mail
Domande frequenti
What is an ASN?
An autonomous system number identifies a network that is run by one organisation and announces its own address ranges on the internet. Large providers have one or more. Looking up the ASN for an address tells you which organisation is responsible for routing traffic to it, which is more reliable than guessing from the address alone.
Does this show where a server is physically?
No. The country shown is where the address block is registered, not where the server or its users are. Companies often register addresses in one country and use them in another, and content networks serve the same address from many places. Treat the result as who runs the network, not as a precise location.
Why does a domain show several networks?
Websites, name servers and mail servers are often run by different companies. A domain might have a website on one cloud provider, DNS at a specialist DNS company and email at a mail service. Listing each role separately helps you see which providers your domain depends on.
What does reverse DNS tell me?
Reverse DNS maps an address back to a name. It is set by whoever controls the address and is often used by mail servers to check that a sender is genuine. We also check the name resolves back to the same address, which is a good sign when it does and worth fixing for mail servers when it does not.
Why is there no network for my address?
Some addresses are not announced on the public internet, for example space that is reserved, not yet in use or only used inside a private network. Private and reserved addresses cannot be looked up at all. If a public address shows no network, it may have been announced only recently or is currently unrouted.
Can I look up IPv6 addresses?
Yes. You can enter an IPv4 address, an IPv6 address or a domain name. For domains we look up both IPv4 and IPv6 addresses where they exist. IPv6 results work the same way, showing the announced range, ASN, registry and reverse DNS name for each address found.