You can use any manual DNS tool, such as “host” or “dig”. You simply check if a DNS entry of type A exist in a respective DNS zone of the BlockList. For example for SpamHaus you check the * zone. The checked IP address must be written reversely.

Example: To check IP, run the following command:

$ host has address

Here the IP is listed in the Block List, because it has a DNS entry.Here the query returned the address – this has a special meaning. What do the 127.0.0.* Return Codes mean?


Return Code Source Notes SBL Spamhaus Maintained reserved for future use XBL CBL Detected Address XBL NJABL Proxies (customized) XBL reserved for future use XBL reserved for future use XBL reserved for future use reserved for future use PBL ISP Maintained PBL Spamhaus Maintained


Source of the table: Usage#200

If the IP is not listed you get the following response:

$ host
Host not found: 3(NXDOMAIN)

The IP can be listed in several lists. In that case you get something like this:

$ host has address has address

You can also get a description or link to further info why was the server blocked, by querying the TXT DNS record of the domain:

$ host -t TXT descriptive text ""


How to manually check if IP is listed in a Block List?
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