IP Lookup

Check any IPv4 or IPv6 address's type, network (ASN), provider, approximate country, reverse DNS and blacklist status — all in one lookup.

What is an IP lookup?

An IP lookup tells you what is known publicly about an IP address: whether it is public or private, which network announces it, the organisation that runs that network, the country the block is registered to, its reverse DNS name and whether it appears on common spam block lists. It works for both IPv4 addresses such as 8.8.8.8 and IPv6 addresses such as 2001:4860:4860::8888.

It is useful whenever an address shows up in a log, an email header or a firewall alert and you want to know where it belongs.

How the IP lookup works

First the address is classified. Only public addresses are routed on the internet, so private, loopback, link-local, multicast and reserved addresses are labelled as such and not looked up further.

For a public address, the tool runs three live checks. Network details come from Team Cymru's IP-to-ASN service, which is built from real internet routing data: the autonomous system number (ASN), the routed network range, the network's name, the regional internet registry and the allocation date. A reverse DNS query looks for a PTR hostname. Finally, IPv4 addresses are checked against three DNS-based block lists: SpamCop, Barracuda and SORBS.

How to use the IP lookup tool

  1. Paste an IPv4 or IPv6 address into the box.
  2. Press Lookup IP.
  3. Read the overview for the address type and PTR hostname.
  4. Check the network information and the reputation results below it.

Understanding your IP lookup results

Type and reverse DNS

The type shows whether the address is public or belongs to a special range. The PTR hostname, if one exists, often reveals the provider or the role of the server, for example a mail server or a home broadband connection.

ASN, provider and network range

The ASN identifies the network that announces the address to the rest of the internet, and the provider name is that network's registered name. The CIDR range is the block of addresses the network routes together.

Approximate country

The country comes from where the address block is registered, not from GPS or a precise location database. It never identifies a person or a street address, and for global networks it may differ from where the server actually sits.

Reputation

Each block list shows Listed, Not listed or Unable to check. A list that could not be queried is left out of the count instead of being treated as clean.

IPv4 and IPv6 addresses

IPv4 addresses are four numbers from 0 to 255 separated by dots, which allows about 4.3 billion addresses in total, no longer enough for every device online. IPv6 uses much longer 128-bit addresses, written as eight groups of hexadecimal digits separated by colons, where a double colon shortens a run of zero groups. This tool accepts both, and one website can have an address of each kind.

Common uses

  • Identifying the network behind an unfamiliar address in server or login logs.
  • Checking which hosting company a website's server belongs to.
  • Seeing whether a mail server's IP appears on a spam block list.
  • Confirming whether an address is public or part of a private network.

Common problems and fixes

"Not a valid address". Remove any port number, such as :443, and any spaces. Enter one address at a time.

No network details. The address may be private or reserved, or very new to routing. Private ranges such as 192.168.x.x only exist inside local networks.

The country looks wrong. Large providers register blocks in one country and use them worldwide, so registration country and server location can differ.

Related tools

Frequently asked questions

Can an IP lookup find someone's home address?

No. An IP lookup shows network information: the provider, the routed address range and the country where the block is registered. Internet providers do not publish which customer uses an address, and this tool has no access to that information. Only the provider can link an address to a customer, normally under legal process.

How accurate is the country shown for an IP address?

It reflects where the address block is registered with its regional internet registry. For most local providers that matches where the address is used. Large cloud and content networks often register blocks in one country and use them worldwide, so the country can differ from the server's real location.

What is an ASN?

An autonomous system number identifies a network that runs its own routing on the internet, such as an internet provider, a hosting company or a large organisation. Every public IP address is announced by at least one ASN, which tells you which network is responsible for routing traffic to it.

Why does the IP lookup say an address is private?

Some ranges, such as 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16, are reserved for local networks and are not reachable on the public internet. The same private address is used inside millions of homes and offices, so it has no public owner, network or reputation to look up.

Does the tool check IPv6 addresses?

Yes. IPv6 addresses are classified and looked up for network details and reverse DNS. Block list checks are run for IPv4 addresses only, because block list coverage for IPv6 is inconsistent and the result would not be reliable enough to show.

What does it mean if an IP is on a block list?

The address was reported for sending spam or other unwanted traffic, at some point, to that list. It is a reputation signal, not proof of current wrongdoing. Shared and recycled addresses can be listed because of a previous user. The IP Blacklist Checker explains next steps.

Why is there no PTR record for this IP?

Reverse DNS is set by whoever controls the address block, usually the hosting provider or internet provider. Many addresses, especially home connections and shared hosting, have none. It is not an error on its own, but mail servers should always have a PTR record to deliver email reliably.