Spamhaus’ primary data sets are published in DNS zones known as DNSBLs. Users of that data ask the zone a question (a “query”) and the zone provides a response – a return code – in the form of an IPv4 IP address within a designated range (RFC1918 internal network). The…

*** This is a Security Bloggers Network syndicated blog from The Spamhaus Project authored by The Spamhaus Team. Read the original post at: https://www.spamhaus.org/resource-hub/dnsbl/spamhaus-dnsbl-return-codes-technical-update