Physical ports on your computer allow communicating with the peripheral devices, while network communication ports will allow communicating with different computers or remote devices. TCP ports 25 or 465 (SMTP and SMPTS), 110 or 995 (POP3 and POP3S), or 143 or 993 (IMAP and IMAPS), showing that an e-mail server is running. Your computer has two types of ports, physical ports, and network communication ports. Is it possible for DNS requests to be made from ports other than UDP Port 53 I have noticed in my router logs several denied requests from random ips that are addressed to my DNS servers. You could also try searching the web for Mikrotik. So you could create a rule to only accept these DNS requests from your specified src-address, on a specified interface, (one for UDP and one TCP) and create another to drop any other requests (one for UDP and one TCP).so four rules in total.
The physical ports on your computer allow communicate with peripheral devices such as your keyboard and mouse and to connect with internet devices via Ethernet cables. UDP and TCP Port 53 are used for DNS requests,etc. Here in this Common Ports cheat sheet, I have described the most commonly used or well-known network communication ports and its associated services, daemons.
