Farsight Security is a cybersecurity intelligence company, now operating as a subsidiary of DomainTools following an acquisition. The company specializes in DNS (Domain Name System) observation data, providing visibility into DNS activity to support threat detection, investigation, enrichment, and mitigation use cases. Farsight's core product is DNSDB, a database that aggregates and indexes passive DNS data — historical and real-time records of DNS resolutions collected from sensors across the internet. This dataset enables security analysts and researchers to trace the history of domain names, IP addresses, and name server relationships, which is useful for uncovering malicious infrastructure, tracking threat actors, and performing incident investigations. Following the DomainTools acquisition, Farsight's DNS observation data is combined with DomainTools' broader internet intelligence data, which includes domain registration (WHOIS) and related data points. This integration is intended to extend the timeline and context available when identifying emerging threats originating outside an organization's network perimeter. Farsight's data and products are primarily used by threat intelligence teams, security operations centers (SOCs), and incident responders. Its resources, user guides, and product interfaces have been migrated to the DomainTools platform. The company's historical focus has been on passive DNS data as a foundational layer for internet infrastructure intelligence and threat analysis.