Check an IP address or domain against DNS blacklists (RBLs), reporting every list that answered, every list that failed, and the coverage of the check.
Enter a value above and run the check to see results here.
Check an IP address or domain against DNS blacklists (RBLs), reporting every list that answered, every list that failed, and the coverage of the check.
Eleven address blacklists (Spamhaus ZEN and XBL, SpamCop, Barracuda, PSBL, UCEPROTECT levels 1 and 2, 0spam, Interserver, Mailspike and SPFBL) and two domain-reputation lists (SURBL multi and Spamhaus DBL). The result lists every one of them with its raw return code.
Because a failed lookup is not evidence of absence. A provider refuses a query with REFUSED, SERVFAIL, a timeout or a dedicated error address such as 127.255.255.254. Those are reported as a failed check, never as a clean result, so an incomplete check can never be mistaken for a good one.
Coverage is the share of configured lists that actually answered. The score is calculated only from the lists that returned a verdict, so a 100 score with 60% coverage means every list that replied found nothing — it does not mean every list was checked.
Some providers only answer queries made from a dedicated resolver with attributable forward and reverse DNS, or through an access key. Those lists are reported as not checked rather than as a clean result, and they reduce the coverage figure so the gap stays visible.
Results are read directly from the blacklists over DNS and cached for up to five minutes so the providers are not over-queried. Blacklist records are published with short lifetimes, so the cached answer is the same answer you would get immediately.
The score only covers the lists that actually answered. A list that refused the query, timed out or is not configured for this deployment is counted as unchecked and lowers the coverage figure instead of lowering the score — so a high score always means the lists that replied found nothing.