A Guide To RAM, ROM, NVRAM, And Flash Cisco CCNA Exam Tutorial

A Guide To RAM, ROM, NVRAM, And Flash Cisco CCNA Exam Tutorial
CCNA exam success depends on knowing the details, & nowhere is this more true than knowing the various components of a Cisco router. This is also where you can quickly start drowning in acronyms! The terms "RAM" & "ROM" probably are not old to you, but keeping up with "what goes where" with RAM, ROM, NVRAM, & Flash Memory can be a challenge! In this tutorial, we'll take a look at all six of these components & their contents.

ROM stands for Read-Only Memory. ROM stores the router’s bootstrap startup program, operating system program, & power-on diagnostic check programs (the POST).

Flash memory is generally referred to as “flash” The Cisco Internetwork Operating System (IOS) images are held here. Flash is erasable & reprogrammable ROM. Flash memory content is retained by the router on power-down or reload.

RAM is short for Random-Access Memory. RAM on a Cisco router stores operational information such as routing tables & the jogging configuration file. RAM contents are lost when the router is powered down or reloaded.

Success on the CCNA exam depends on keeping these terms straight & knowing their contents. Know the contents of each, pay special attention to what is lost on a reload & what is not, & you are on your way to CCNA exam success!

NVRAM is non-volatile RAM. By "non-volatile", they mean that the contents of NVRAM are not lost when the router is powered down or reloaded. Where RAM holds the jogging configuration file, NVRAM holds the startup configuration file. If NVRAM is empty when the router reloads, you will be prompted to enter setup mode.