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) or Subversion to maintain history of changes.

RANCID does this by the very simple process summarized 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,
• email any differences (sample) from the previous collection to a mail list,
• and finally commit those changes to the revision control system