https://www.renemoser.net/tags/dnsbl/Recent content in Dnsbl on René MoserHugoen-usTue, 09 Dec 2008 00:00:00 +0000https://www.renemoser.net/blog/2008/12/09/use-dns-blacklists-in-php/Tue, 09 Dec 2008 00:00:00 +0000https://www.renemoser.net/blog/2008/12/09/use-dns-blacklists-in-php/A DNS blacklist (DNSBL) is queried like any other DNS name: reverse the octets of the address you want to check, append the zone of the list, and resolve it. If the name resolves, the address is listed. No API keys, no HTTP client, no library — a resolver is all you need. The snippet below checks one address against a list of DNSBL zones and stops at the first hit.