D 解析：Explanation:About 99 percent of the time someone uses a config-register, it's more than likely because of a lost router password. Normally, the two config-registers for recovering passwords are 0x2102 and 0x2142.The first config-register, 0x2102, is the normal config-register if you boot the router from internal Flash. You can see this config-register by using the show version command. In this output, you'll notice the last line says, "Configuration register is 0x2102." This is normal.