Internet Protocols are something I learned about as I set up servers to service outside requests from the internet. I was mostly interested in using web and mail services, but started looking into VPN and other various services that can be provided. I wasn't dealing with high-end hardware, so I didn't want to get into storage or SQL servers. One of my earliest lessons on protocols was when I was a Field Technician. The hardware companies would send me out to replace modems and network cards all the time. I found that replacing the TCP/IP protocols and reinstalling them would fix it almost every time. I was still forced to swap the part though.
Protocols are something us users do not have to interact with much anymore. They used to be more important if you were connecting to other services such as Telnet or text services. You needed to have those protocols installed on your computer's network interface card to connect to the service. Now-a-days, most internet activity takes place on Port:80 using TCP/IP, which is for normal web-browsing. Secure internet connections use TCP/IP also, but port 443 for direct secure connections to the host. As an administrator, I had to know about a dozen others for turning off and on for access by clients from the external network (the internet). After a little research, it appears that Port:25 isn't used for mail services anymore and has moved to Port: 587. These can change over time and hopefully you know where to keep abreast of these changes if you are an admin.
Watching what ports are open and closed, while also monitoring the server's logs will help you run a secure operation.