Check whether an IP address or a domain is listed on common DNS-based blocklists (DNSBLs / RBLs / URIBLs).
Check an IP or domain
IPv4, IPv6, and domains are supported. Private and link-local addresses are rejected — DNSBLs don't list those. IPv6 is only checked against zones that support it (e.g. Spamhaus ZEN); v4-only zones are marked accordingly.