Safe search is a list of set IP addresses that is meant to pre-enable the safe search of search portals.
This zone file contains all known IP to spoof safe search enabled search sites
There are different approaches of spoof domains depending on the resolver used for this.
For example in PowerDns Dnsdist you will do it like this:
addAction('duckduckgo.com.', SpoofCNAMEAction('safe.duckduckgo.com.'))
In standard RPZ you will do it like this:
duckduckgo.com IN CNAME safe.duckduckgo.com
In unbound you need to assign IP spoofing like this
local-zone: "duckduckgo.com." redirect
local-data: "duckduckgo.com. IN CNAME safe.duckduckgo.com."
In hosts file you forced to have a tremendous big list of IP host like this
54.229.105.151 duckduckgo.com
79.125.105.136 duckduckgo.com
79.125.106.1 duckduckgo.com