DNSDB is a database of both passive and authoritative DNS data. Passive data comes from Farsight Security's Security Information Exchange while authoritative data is provided by various zone operators. DNSDB allows users to easily search for individual RRsets and provides additional metadata as well. It can also perform inverse, or RDATA, searches. Developers can use DNSDB's REST API to make automated bulk queries against DNSDB in JSON format.