I haven't been able to find any information that explains my question. Maybe it's too elementary or I'm overthinking the concept. I have 5 servers in a multiserver setup. Is my idea of how ports work correctly? I'm guessing that a DNS server needs port 80 and 443 open to communicate with the web server on the flip side I'm guessing the web server needs port 53 open to talking to the DNS and 3306 open to talking to MYSQL. Is this wrong or right and please explain or link me to why.. Thanks
If you run a multiserver-setup tcp 3306 OUT must be allowed on all slaves and (at least) the master must allow tcp 3306 IN dns: tcp + udp 53 web: 80,443,20,21,990 mail: 25,106,110,143,465,587,993,995
