IP address lookup

IP WHOIS Lookup: Find the Network and Organization Behind an IP

An IP WHOIS lookup returns registration information for an IP address: its network range, organization, country and regional registry, plus technical and abuse contacts where published by the registry.

What an IP lookup can show

The address range and CIDR block containing the IP address.
The network name and registered organization, where published by the registry.
The country recorded in registration data and the Regional Internet Registry (RIR).
Abuse and technical contact details published by the registry.

Who allocates IP addresses?

IANA supplies IP address pools to RIRs. The five RIRs are AFRINIC, APNIC, ARIN, LACNIC and RIPE NCC.

APNIC serves the Asia Pacific region and lists TWNIC among its National Internet Registries (NIRs).
TWNIC provides IP address allocation, assignment and registration management, including distribution to network users through authorized providers.

Reading network and organization fields

APNIC uses inetnum for IPv4 address ranges and inet6num for IPv6 ranges. ARIN uses NetRange and CIDR for the address range and its CIDR notation.

APNIC’s netname and ARIN’s NetName identify the network name.
APNIC’s descr provides descriptive information; ARIN’s OrgName identifies the organization.
APNIC’s last-modified is the timestamp of the database object’s last modification.

WHOIS and RDAP for IP addresses

WHOIS uses TCP port 43. RFC 9082 defines RDAP query formats for IP networks, and RFC 9083 defines JSON response formats.

RFC 9224 defines how to find the authoritative RDAP service; discovery for an IP address uses the longest matching prefix.
IANA maintains separate IPv4 and IPv6 RDAP bootstrap files for finding the corresponding service.

Registered country is not physical location

APNIC defines country by the country or economy where admin-c is based. RIPE explicitly warns that country cannot reliably map an IP address to its physical country of use.

Do not use the registered country to determine a user’s or server’s physical location.
APNIC permits nonpublic customer assignments. Queries for these return the upstream provider’s registration information and need not identify an individual user.

Private and special-purpose addresses

IANA has no record of local users of private addresses. For example, its WHOIS record for 10.0.0.0 identifies a private-use reservation, not an individual user.

RFC 1918 reserves 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 for private IPv4 networks.
100.64.0.0/10 is Shared Address Space defined by RFC 6598, distinct from RFC 1918 private addresses.
For IPv6, ::1/128 is the loopback address and fe80::/10 is link-local unicast space.

Finding technical and abuse contacts

RIPE’s tech-c references a technical contact; abuse-c references a role object containing abuse-contact details. Choose the published contact that matches the issue.

ARIN’s WHOIS example uses OrgAbuseEmail for the organization’s abuse-contact email.
An ARIN registration record does not mean ARIN operates the network or polices how its IP addresses are used.

Read an IP lookup result in four steps

Enter an IP address
Enter an IPv4 or IPv6 address above and press Enter to look it up.
Check the network and organization
Read the address range, CIDR block, network name and registered organization for the address you entered.
Interpret the country field
Treat the country field as registration information, not evidence of the user’s physical location.
Choose a contact
If you need to get in touch, use the published technical or abuse contact that matches your issue.

IP WHOIS lookup questions

Can IP WHOIS identify a person?

An IP WHOIS result alone cannot establish a person’s identity. APNIC permits nonpublic customer assignments, for which queries return the upstream provider’s registration information.

Is the country field the IP address’s actual location?

No. APNIC defines country by the administrative contact’s country or economy. RIPE also warns that the field cannot reliably map an IP address to its physical country of use.

Why can’t I identify the user of a private IP address?

Private addresses can be used without informing IANA, so it has no record of their local users. A lookup may still return a reservation record, as IANA WHOIS does for 10.0.0.0.

Who manages IP addresses in Taiwan?

APNIC serves the Asia Pacific region and lists TWNIC as an NIR. TWNIC provides IP address allocation, assignment and registration management, including distribution to network users through authorized providers.

Does the lookup work for IPv6?

Yes. Enter an IPv6 address to look it up. APNIC’s inet6num object describes IPv6 ranges, and IANA maintains a separate IPv6 RDAP bootstrap file.