The Spamhaus DBL is intended to be used to find domains that have poor reputations of sending spam. According to their documentation you should be able to test that it is working by looking up the host or dig response for ‘dbltest.com.dbl.spamhaus.org’ and it should respond with ‘dbltest.com.dbl.spamhaus.org IN A 127.0.1.2’. However this is what I get: The host results