IP Lookup

Every public IP address is registered to an organization and announced by a specific network - this lookup shows both, plus who else knows an address by its hostname or approximate location.

Reverse DNS (PTR)

The hostname an IP address itself points back to - the opposite direction of a normal A record. Mail servers commonly check it before accepting a message; plenty of addresses, especially residential ones, have none at all.

Registry record (RDAP)

Every public IP address belongs to a block assigned by one of five regional registries (ARIN, RIPE, APNIC, LACNIC, AFRINIC) to an organization - an ISP, a hosting company, a business. RDAP is the modern, structured way to ask that registry who a given address belongs to.

ASN

The Autonomous System Number identifies the specific network that announces this address to the rest of the internet - often the same organization as the registry record, but not always, since one company can announce address space registered to another.

Geolocation accuracy

Approximate, not exact - it comes from where an address is registered or commonly seen, not GPS. Usually right to the city or region for a home connection, but can be badly off for a large ISP, VPN, or CDN address that serves a whole country from one listed location.

Want the network-level view - registered prefixes and the network operator - instead of one address? See ASN Lookup.