Cisco routers and switches use two configuration files. Where is the configuration file used at device bootup stored? A. RAM B. ROM C. Flash D. NVRAM Solution D is correct. The startup configuration is used during the device bootup process and is stored in NVRAM—a nonvolatile storage location retaining all information after power off. A, B, and C are incorrect. A is incorrect because RAM is volatile and is used to store the running configuration. B is incorrect because ROM holds a bootstrap program and the ROMMON basic operating system. C is incorrect because flash memory holds a copy of the IOS..