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

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 *.zen.spamhaus.org zone. The checked IP address must be written reversely.

Example: To check IP 85.237.226.41, run the following command:

$ host 41.226.237.85.zen.spamhaus.org
41.226.237.85.zen.spamhaus.org has address 127.0.0.4

Here the IP is listed in the Block List, because it has a DNS entry.Here the query returned the address 127.0.0.4 – this has a special meaning. What do the 127.0.0.* Return Codes mean?

Source of the table: http://www.spamhaus.org/faq/answers.lasso?section=DNSBL Usage#200

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

$ host 48.41.9.158.zen.spamhaus.org
Host 48.41.9.158.zen.spamhaus.org not found: 3(NXDOMAIN)

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

$ host 48.41.9.58.zen.spamhaus.org
48.41.9.58.zen.spamhaus.org has address 127.0.0.4
48.41.9.58.zen.spamhaus.org has address 127.0.0.11

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 41.226.237.85.zen.spamhaus.org
41.226.237.85.zen.spamhaus.org descriptive text "http://www.spamhaus.org/query/bl?ip=85.237.226.41"

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