Show Version Command in Cisco IOS

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:

On Routers

  • 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

Cisco switches

  • The number of Ethernet switching interfaces
  • The serial numbers of the device and its power supplies
  • The MAC address of the switch
  • The revision number of the motherboard
  • The model number of the switch
  • Whether you’ve enabled password recovery

PIX firewalls

  • 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!

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