RANCID monitors a router's (or more generally a device's) configuration, including software and hardware (cards, serial numbers, etc) and uses CVS (Concurrent Version System) to maintain history of changes.

RANCID does this by the very simple process summarised as:

• login to each device in the router table (router.db),
• run various commands to get the information that will be saved,
• cook the output; re-format, remove oscillating or incrementing data,
• and finally commit those changes to the revision control system