Show Version Command in Cisco IOS

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Show Version is a great command for routers, switches or PIX firewalls.

Here is a look at all the things you can verify with the show version command:

The version of the IOS operating system
The version of the ROM bootstrap
The version of the boot loader
How someone last powered on the device (In addition to powering on in the usual manner, you can also power on a device with a system reset (i.e., warm reboot) or by a system panic.)
The time and date the system last started
The “uptime” for the system (i.e., how much time has passed since the last power-on)
The image file that the device last started (i.e., the actual path to the IOS software)
How much RAM the device has
The processor board ID, which you can use to determine the version of the device’s motherboard
The number and type of each interface on the device (e.g., Qty 2 Ethernet, Qty 6 Serial, etc.)
The number of terminal lines on the router if a router has asynchronous serial lines attached
The amount of nonvolatile RAM (NVRAM), used to hold the SAVED version of the configuration file, also known as the startup-configuration
The amount and type of Flash on the device (except on a switch), used to hold the operating system when it isn’t in use (Think of it as the equivalent to a hard drive on a PC.)
The configuration register on the device, which is a hexadecimal number used to tell the device what to do when it boots. (Typically, this only changes when you need to bypass the configuration file because of a lost password, but you can also change it for other special cases.)
The hostname of the device

The MAC addresses for the interfaces
Which licenses you’ve enabled for which features (such as failover, 3DES encryption, or number of hosts)
The activation key for those licenses
The last time someone modified the configuration file

We hope this helps and saves you time finding all this information by putting it in one place!