Chapter 4: Cisco's Internetworking Operating System (IOS)

1. C. The exec-timeout command is set in minutes and seconds.
2. D. The auxiliary port can be configured with modem commands so that a modem can be connected to the router. It lets you dial up a remote router and attach to the auxiliary port if the router is down and you need to configure it out-of-band (meaning out of the network).
3. C, D. To configure SSH on your router, you need to set the username command; the ip domain-name, login local, and the transport input ssh under the VTY lines; and the crypto key command under global configuration mode. However, SSH version 2 is not required but suggested.
4. C. The show controllers serial 0 command will show you whether either a DTE or DCE cable is connected to the interface. If it is a DCE connection, you need to add clocking with the clock rate command.
5. C. The default locations of the files are IOS in flash memory, start-up configuration in NVRAM, and running configuration in RAM.
6. B. The command service password-encryption, from global configuration mode, will encrypt all current and future passwords.
7. B. From global configuration mode, use the line vty 0 4 command to set all five default VTY lines.
8. C. The enable secret password is case sensitive, so the second option is wrong. To set the enable secret password, use the enable secret password command from global configuration mode.
9. C. The typical banner is a message of the day (MOTD) and is set by using the global configuration mode command banner motd.
10. C. The prompts offered as options indicate the following modes:

    router(config)#—global configuration mode

    router>—user mode

    router#—privileged mode

    router(config-if)#—interface configuration mode

11. D. To copy the running-config to NVRAM so that it will be used if the router is restarted, use the copy running-config startup-config command in privileged mode (copy run start for short). Option C is wrong because it's at the wrong prompt.
12. D. To allow a VTY (Telnet) session into your router, you must set the VTY password. Option C is wrong because it is setting the password on the wrong router.
13. D. The erase startup-config command erases the contents of NVRAM and will put you in setup mode if the router is restarted.
14. B. If an interface is shut down, the show interface command will show the interface as administratively down. (It is possible that no cable is attached as well, but you can't tell that from this message.)
15. C. With the show interfaces command, you can view the configurable parameters, get statistics for the interfaces on the router, verify if the interfaces are shut down, and see the IP address of each interface.
16. C. If you delete the startup-config and reload the router, the router will automatically enter setup mode. You can also type setup from privileged mode at any time.
17. D. You can view the interface statistics from user mode, but the command is show interface serial 0/0.
18. B. The % ambiguous command error means that there is more than one possible show command that starts with ru. Use a question mark to find the correct command.
19. B, D. The commands show interfaces and show ip interface will show you the layer 1 and 2 status and the IP addresses of your router's interfaces.
20. A. If you see that a serial interface and the protocol are both down, then you have a Physical layer problem. If you see serial1 is up, line protocol is down, then you are not receiving (Data Link) keepalives from the remote end.