7 Network Protocols Every IT Engineer Should Master (Before It's Too Late)

"It's not what you don't know that gets you into trouble, it's what you know for sure that just isn't so." – Mark Twain

In IT, it’s easy to think you have everything under control—until an unexpected issue proves otherwise. From a website that won’t load to emails disappearing without explanation, many of the most frustrating problems stem from misconfigured or misunderstood network protocols.

Today, I'll walk you through the 7 most important network protocols, real-world cases where a lack of understanding caused problems, and, more importantly, how those problems were solved. Because in tech, it’s not just about avoiding mistakes—it’s about knowing how to fix them when they happen.

1. HTTP & HTTPS: When a Client’s Website Lost Credibility

The Problem

A client had an online store, but sales were dropping drastically. When we checked, we noticed that their browser displayed a "Not Secure" warning every time someone visited.

Cause

Their site was using HTTP instead of HTTPS (port 80 instead of 443). This meant that data, including passwords and payment information, could be intercepted.

Solution

? Installed an SSL/TLS certificate on their server. ? Configured the website to redirect all HTTP traffic to HTTPS. ? Within 24 hours, the "Not Secure" warning disappeared, and customer trust returned.

?? Lesson: HTTPS is mandatory for any serious website today. Without it, browsers will warn users, making them leave immediately.

2. SSH: When an Administrator Locked Himself Out of His Own Server

The Problem

A system administrator wanted to improve security by disabling password logins for SSH (port 22) and requiring key authentication. However, he forgot to upload his key before making the change, locking himself out of the system.

Cause

SSH was configured to only allow key-based authentication, but the administrator hadn't added his public key beforehand.

Solution

? Used physical access to the server to log in with a local account. ? Modified the SSH configuration and uploaded the correct key. ? Set up an emergency user with limited access to prevent future lockouts.

?? Lesson: Before making critical SSH changes, always test the new configuration in another session before closing the current one.

3. FTP: When Two Teams Overwrote Each Other’s Files Without Knowing It

The Problem

A team of developers was updating a website using FTP (port 21). Without realizing it, two people were uploading files at the same time, overwriting each other’s changes and causing errors on the site.

Cause

FTP does not have version control or file-locking, leading to conflicts when multiple users work on the same site.

Solution

? Switched from FTP to SFTP (which is more secure). ? Implemented a version control system (Git) to avoid accidental overwrites. ? Now, all changes go through a central repository before being uploaded to the server.

?? Lesson: FTP is useful, but in collaborative environments, SFTP with version control is a must to prevent issues.

4. SMTP: When a Company’s Emails Kept Landing in Spam

The Problem

A client reported that their emails were going straight to recipients' spam folders, even though they were legitimate messages.

Cause

The SMTP server (port 25) was sending emails without proper security configurations, making spam filters flag them as suspicious.

Solution

? Configured SPF, DKIM, and DMARC to authenticate emails. ? Migrated the email service to a reputable provider with an established sending reputation. ? Within 48 hours, emails were landing in inboxes again.

?? Lesson: Without proper authentication, even legitimate emails can be flagged as spam.

5. DNS: When a Website Seems to Disappear

The Problem

A company migrated their website to a new server, but after the move, some users couldn’t access it and were still seeing the old version.

Cause

The DNS records (port 53) took time to propagate. Some internet providers were still resolving the old IP, while others had updated to the new one.

Solution

? Reduced the TTL (Time to Live) on DNS records before migration to speed up propagation. ? Used a global DNS provider with distributed caching to minimize future issues.

?? Lesson: When making DNS changes, it can take up to 48 hours for all users to see the updated site.

6. MySQL: When a Developer Deleted an Entire Database Without a Backup

The Problem

A developer ran a command on MySQL (port 3306) without checking it properly, and accidentally deleted the entire production database.

Cause

There were no automatic backups in place, and the only existing backup was two weeks old.

Solution

? Restored the latest available backup. ? Implemented daily automated backups and set up a staging environment to test changes before applying them to production.

?? Lesson: Never make changes in production without a recent backup.

7. RDP: When a Hacker Tried to Access a Support Server

The Problem

A tech support team had RDP (port 3389) enabled on a server without IP restrictions. One morning, they detected hundreds of login attempts from unknown locations.

Cause

RDP was exposed to the internet without proper security measures, making it a target for brute-force attacks.

Solution

? Restricted access to a private VPN. ? Enabled two-factor authentication for remote logins. ? Reviewed logs to ensure no unauthorized access had occurred.

?? Lesson: If you use RDP, never leave it open without restrictions.

Conclusion: It’s Not a Matter of If Something Will Break—It’s When

"Learning from others’ mistakes is cheaper than learning from your own."

Networking and protocol issues are not a question of if they’ll happen, but when. The difference between a good IT engineer and a great one is their ability to anticipate these errors and quickly resolve them when they occur.

Which of these problems have you faced? Share your experience in the comments!

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