Blog

Four weeks after the first complete sweep of the IPv4 reverse DNS space, we re-crawled every address whose answer could have changed — 1.75B targets with a far more patient timeout budget. The result: 120.5M newly resolved hostnames, a measured PTR churn rate of 0.23% per month, and an updated Reverse DNS Database that now holds 1.16B PTR records — +11.4% over the July release. This update covers what the 561 million July timeouts really were, how much a billion-record dataset changes in 27 days, and the merge semantics that keep a maintained dataset honest.

Every month, our distributed crawler resolves the PTR record of all 3.7 billion routable IPv4 addresses and compresses 1.04 billion reverse DNS hostnames into a single gigabyte. This article explains how the crawl works and how a billion hostnames turn into IP intelligence: hosting detection, purity-verified VPN and Tor rules, and 511 million IPs geolocated from operator naming conventions — plus the latest research, from CAIDA's Hoiho to LLM-guided extraction.

An empirical analysis comparing ten major IP geolocation providers against GPS ground truth data collected from real website visitors. This study evaluates accuracy using the Haversine distance formula after filtering non-residential traffic (datacenters, VPNs, proxies). Results show correct rates (≤50 km) ranging from ~50% to ~75% across providers.

This blog post examines 109 randomly selected IP addresses to measure the accuracy of IP to Company data that is inferred from WHOIS data. Discover why ipapi.is delivers 98% accuracy while top IP API competitors cannot provide accurate company data.

This blog post illustrates why ipapi.is surpasses ipinfo.io in terms of company and ASN data accuracy. Several samples of IP addresses and ASNs are looked up on both API providers and the results are compared. It turns out that ipinfo.io often fails to find the correct organization name and organization type, which has a significant impact on the accuracy of the API.