An example of domains check with regex in the dns cache of mikrotik

FindYoutbeDomains.rsc

:foreach i in=[/ip dns cache find name~"(youtube-ui.l.google.com|youtube.com|googlevideo.com)\$" && $type ~ "^(A|CNAME)\$" ] do={
    :local tmpAddress [/ip dns cache get $i data];
    :local cacheName [/ip dns cache get $i name] ;
    delay delay-time=10ms
    
    :if ( [/ip firewall address-list find where address=$tmpAddress list=YOUTUBE_DOMAINS ] = "") do={         
        :log info ("added entry: $cacheName  $tmpAddress");
        /ip firewall address-list add address=$tmpAddress list=YOUTUBE_DOMAINS comment=$cacheName;
    }
}