Router Components
RAM – holds packet buffers, ARP cache, routing table, software and data structure that allows the router to function; running-config is stored in RAM, as well as the decompressed IOS in later router models
ROM – starts and maintains the router
Flash memory – holds the IOS; is not erased when the router is reloaded; is an EEPROM [Electrically Erasable Programmable Read-Only Memory] created by Intel, that can be erased and reprogrammed repeatedly through an application of higher than normal electric voltage
NVRAM – Non-Volatile RAM - holds router configuration; is not erased when router is reloaded