Lecture 2.4 Saving, Reloading & Managing Cisco Configs | Running vs Startup
You just spent an hour configuring a router. Power blinks. All your work is gone. Welcome to the single most important lesson new network engineers learn the hard way — if you don't save it, you don't have it. In this lecture, we make sure that never happens to you.
We break down the difference between the running configuration and the startup configuration, how to save your work properly, how to reload a device safely, and how to back up and restore configurations so you can recover from any mistake.
🎯 WHAT YOU'LL LEARN
The difference between running-config and startup-config
How Cisco devices use RAM, NVRAM, and flash memory
How to save configurations the right way
How to reload a device and what to expect
How to back up configurations to a TFTP or FTP server
How to restore a configuration when things go wrong
How to completely wipe a device and start fresh
🧠 THE TWO CONFIGURATIONS THAT MATTER
1️⃣ RUNNING CONFIGURATION
Lives in RAM — the device's active memory
Reflects everything currently working on the device
Changes take effect the moment you type them
Disappears completely when the device loses power
Viewed with the show running-config command
2️⃣ STARTUP CONFIGURATION
Lives in NVRAM — non-volatile memory that survives reboots
Loaded into RAM every time the device powers on
This is the configuration the device "remembers"
Viewed with the show startup-config command
The golden rule: changes are only permanent once you copy the running configuration to the startup configuration.
💾 SAVING YOUR WORK — THREE WAYS
Method 1 — the full command:
copy running-config startup-config
Method 2 — the shortened version:
copy run start
Method 3 — the legacy shortcut (still works on most IOS versions):
write memory, or simply wr
All three do the exact same thing. Pick one and stick with it — we use copy run start throughout this course because it's the most readable.
🔄 RELOADING A DEVICE
The reload command restarts the router or switch. IOS asks:
"System configuration has been modified. Save?" — if you say no, you lose unsaved changes
"Proceed with reload?" — confirm to restart
After reload, the device boots from the startup configuration. This is why saving matters — whatever isn't saved is gone forever after reload.
💡 PRO TIP: reload in 5
If you're working remotely and about to make a risky change, type: reload in 5
This schedules a reload in 5 minutes. If your change locks you out, the device reboots itself back to the last saved config. It's the single best safety net in networking.
Cancel the scheduled reload with: reload cancel
📤 BACKING UP A CONFIGURATION
Back up to a TFTP server:
copy running-config tftp
IOS will ask for the server IP address and the destination filename. This saves a full text copy of your configuration to an external server — your first real backup strategy.
For this course, we also cover:
Copying configs to flash memory on the device itself
Exporting configurations as text files from Packet Tracer
Keeping version-controlled backups of every lab
⚠️ Use this carefully in production. In a lab, wipe and reset as often as you need — it's one of the best ways to learn.
⚠️ COMMON MISTAKES THAT COST HOURS
Making changes and forgetting to save — one power blip and it's gone
Copying startup to running instead of the other way around — this overwrites your current work
Forgetting which config you're editing — always check the prompt and run show commands
Saving a broken configuration, then rebooting — now your broken config is permanent
Not keeping external backups — flash and NVRAM can fail
🧪 HANDS-ON LAB
In Packet Tracer:
Open a router and change the hostname
View the running config — confirm your change is there
View the startup config — confirm it's NOT there yet
Save with copy run start
Reload the device
Verify the hostname persists after reboot
Bonus: wipe the device with erase startup-config, reload, and watch it boot clean
Repeat this cycle until saving feels as automatic as breathing.
🏢 ABOUT DARGSLAN NETWORKING
Dargslan publishes practical, lab-driven technical books. This video series is the companion to our CCNA Lab Guide book — built on the principle that real skills come from real labs, done repeatedly.
▶️ NEXT UP
Section 3 — we leave the single-device world behind and start building real network topologies with routers, switches, and PCs talking to each other.
🔔 Subscribe and hit the bell so you don't miss the first real topology lab. Got a horror story about losing a config? Share it in the comments — we've all been there.
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