dnsmasq

dnsmasq is called with arguments:

ps -fwwaux | grep dnsmasq
 
/usr/local/sbin/dnsmasq --all-servers --rebind-localhost-ok --stop-dns-rebind -H /var/etc/dnsmasq-hosts --port=53 --bogus-priv \
--server=/lan.example.com/192.168.0.1 \
--rebind-domain-ok=/lan.example.com/ \
--strict-order --domain-needed --dns-forward-max=5000 --cache-size=10000 --local-ttl=1 \
--conf-dir=/usr/local/etc/dnsmasq.conf.d,*.conf

Not all options can be set from OPNSense Web UI. To add some customisation:

ipset=/youtube.com/ytimg.com/googlevideo.com/youtube
ipset=/freeconet.pl/fcn.pl/voip
address=/doc.gitlab.example.com/192.168.0.240

Note: above address entry means:

Specify an IP address to return for any host in the given domains. Queries in the domains are never forwarded and always replied to with the specified IP address which may be IPv4 or IPv6.