Unfortunately, Yahoo does not yet have a DNS-level SafeSearch enforcement option. At the moment, the only way that Yahoo can be forced into SafeSearch mode is via an https proxy; the method currently in use by many schools and businesses, however there is a workaround to prevent inappropriate visuals from being displayed in search. All you would have to do is block the following domains: images.search.yahoo.com, video.search.yahoo.com. My script should already block these domains. If you are not comfortable with this workaround, then you could just block Yahoo entirely, if nobody on your network uses it. An example of an upstream DNS provider that blocks these domains is CleanBrowsing.org, when set to the Family Filter mode. I will be updating the script here soon to have the list of hosts pulled from github, and that way users can suggest new search providers to blocked or forced into SafeSearch mode.