Cisco IOS MD5 File Verification
The MD5 File Validation feature allows you to check the integrity of a Cisco IOS software image by comparing its MD5 checksum value against a known MD5 checksum value for the image. MD5 values are now made available on Cisco.com for all Cisco IOS software images for comparison against local system image values.
You will use the /md5 option with the verify command to validate the integrity of an IOS image stored on your Cisco device.
MD5 File Validation gives you a quick and easy method of checking the integrity of an IOS image stored on your Cisco device. I suggest running this quick validation prior to completing an IOS upgrade on your Cisco devices. It's much better to catch a corrupted IOS image early in the IOS upgrade process as it can easily be fixed and avoid the much more painful process of booting a corrupted image.