Manual:$wgDnsBlacklistUrls/en

Details
List of DNS blacklists to use, if  is true. This replaces.

Changes in 1.19
Array values can either be a string containing the URL of the DNS blacklist, or an array containing the URL of the blacklist and an associated "key" should the blacklist require one.

Example
You should end the domain name with a " " to avoid searching your eventual domain search suffixes.