Lab Objective
Back up a router's current configuration to a TFTP server, make a deliberate unwanted change to the configuration, then restore the router to its previously backed-up state and verify the unwanted change is gone.
Lab Purpose
A configuration backup taken before a risky change is standard practice before any significant maintenance activity, providing a fast, reliable way to revert if something goes wrong rather than manually reconstructing a configuration from memory or scattered notes.
Lab Topology
R1 ---- Gi0/0: 192.168.85.1/24
TFTP server: 192.168.85.100/24Task 1: Configure Basic Addressing
Configure R1's interface connecting to the TFTP server's segment.
Task 2: Back Up the Current Configuration
Copy R1's running configuration to the TFTP server.
Task 3: Make an Unwanted Configuration Change
Deliberately change R1's hostname and remove a loopback interface, simulating an unintended or mistaken configuration change.
Task 4: Verify the Unwanted State
Confirm the hostname has changed and the loopback interface is gone.
Task 5: Restore from the Backup
Copy the backed-up configuration from the TFTP server back onto R1.
Task 6: Verify the Restoration
Confirm the hostname and loopback interface match the original backed-up state.
Solution and Verification
R1(config)# interface gigabitethernet0/0
R1(config-if)# ip address 192.168.85.1 255.255.255.0
R1(config-if)# no shutdown
R1(config-if)# exit
R1(config)# interface loopback0
R1(config-if)# ip address 10.99.1.1 255.255.255.255
R1(config-if)# exit
R1(config)# endR1# copy running-config tftp:
Address or name of remote host []? 192.168.85.100
Destination filename [r1-confg]? R1-backup.txt
Writing R1-backup.txt !!
1284 bytes copied in 1.294 secsR1(config)# hostname R1-BROKEN
R1-BROKEN(config)# no interface loopback0
R1-BROKEN(config)# endR1-BROKEN# show ip interface brief | include Loopback
-- (no output -- loopback0 is gone)
R1-BROKEN# show running-config | include hostname
hostname R1-BROKENR1-BROKEN# copy tftp: running-config
Address or name of remote host []? 192.168.85.100
Source filename []? R1-backup.txt
Destination filename [running-config]?
Accessing tftp://192.168.85.100/R1-backup.txt...
Loading R1-backup.txt from 192.168.85.100
1284 bytes copied in 1.156 secsR1# show running-config | include hostname
hostname R1
-- Hostname restored
R1# show ip interface brief | include Loopback
Loopback0 10.99.1.1 YES manual up up
-- Loopback interface restoredKey Takeaway
Restoring from a backup with copy tftp: running-config merges the backup into the currently running configuration rather than fully replacing it — any configuration added after the backup was taken but not present in the backed-up file may still remain, so verifying the final state after a restore, as done here, is essential rather than assuming a restore perfectly recreates the exact backed-up state.