How to test an IP address against an RBL/DNSBL list

Hey There; this post is a technical post about how to test to see if your IP address is on an RBL list.

  1. Locate an RBL provider or if you know you are on their list determine their zone name:  for example the zone names for SPAMHAUS are, and

  2. Once you have those names, you need your IP address.  For this example we will use a fake address:

    (For those of you not in the know, this IP address can’t exist in the IP v4 numbering system)

  3. Now reverse the IP address!


  4. Now we need a command prompt; from windows XP, 2000 or Vista go to START -> Run and type cmd and enter.  In Linux or another *nix system open a terminal.  On Mac OSX, uh, open the terminal.
  5. At the command prompt type nslookup and hit ENTER

    You should see something like this:

    Address:  xx.xx.xx.xx

    *** can’t find Non-
    existent domain

  6. If you DON’T See “Non-Existent domain” and instead see something like:

    Non-authoritative answer:

    It’s a good bet you are on the RBL (in this case SBL) list.

  7. You can repeat this test for each DNSBL zone (ie nslookup
  8. If all the tests come up as “non-existent domain” you’re clean!