Which type of memory retains configuration settings even when the power is turned off?

NVRAM, or Non-Volatile Random Access Memory, is specifically designed to retain its contents even when the power is turned off. This characteristic makes it ideal for storing configuration settings in network devices, such as routers and switches. When a device powers down, the configurations that have been saved in NVRAM are preserved and can be accessed again when the device is restarted.

In contrast, RAM (Random Access Memory) is volatile memory that loses its contents when the power is turned off, making it unsuitable for storing configuration settings over time. ROM (Read-Only Memory) can retain its contents without power, but it is typically used for firmware and initial boot instructions rather than for dynamic configuration settings. Cache memory is a high-speed form of volatile memory that improves data access speed for the CPU but does not retain information without power.

Thus, the unique properties of NVRAM, particularly its non-volatility and its specific use in network device configurations, confirm it as the correct choice for retaining settings even when the power is turned off.