While both work, show inventory is cleaner if you only need the ID. show version is better if you need to verify that the serial number matches the current software version or license entitlements.
This command is crucial for newer devices running ASA code on Firepower hardware (e.g., ASA 5506-X, 5508-X, 5516-X, or the 4100/9300 series). In these devices, the “ASA” is often a software module running on top of a Firepower chassis (FXOS). cisco asa serial number command
If your ASA has removable modules (like a 4-port Gigabit Ethernet module or a SSP (Scalable Security Processor)), show inventory lists the serial number for every component. This is vital because if the main board fails, you may need the sub-module serials for RMA. While both work, show inventory is cleaner if
Scrolling through the output, you will find a line similar to one of these: In these devices, the “ASA” is often a