For public users to use Infotek's DNS resolver, copy & paste the script below in your Mikrotik's router Terminal then press enter.
# Start Script
:global VPNName "DNS-Infotek";
:global VPNServer "dns.infotek.net.id";
:global VPNUser "dns";
:global VPNPass "dnsinfotek";
:global newDNS "10.116.14.1";
:global currentDNS [/ip dns get servers];
/interface l2tp-client add name="$VPNName" connect-to=$VPNServer user=$VPNUser password=$VPNPass add-default-route=no disabled=no
:log info ("Adding L2TP $VPNName for DNS request to Infotek.");
/ip dns set servers="$newDNS,$currentDNS";
:log info ("Adding Infotek's $newDNS DNS server as the first DNS resolver.");
:log info ("Done.");
# End Script