Chapter 6 Exam Essentials Flashcards
Describe the responsibilities of the IOS
It is a proprietary kernel that provides routing, switching, internet working, and telecommunications features.
The core function of Cisco IOS is to enable data communications between network nodes. In addition to routing and switching, Cisco IOS offers dozens of additional services that an administrator can use to improve the performance and security of network traffic.
The Cisco router IOS software is responsible:
- Carrying network protocols and functions
- Connecting high-speed traffic between devices
- Adding security to control access and prevent unauthorized network use
- Providing scalability for ease of network growth and redundancy
- Supplying network reliability for connecting to network resources
List the options available to connect to a Cisco device for management purposes
The three options available are the console port, auxiliary port, and in-band communication, such as Telnet, SSH, and HTTP. Don’t forget, a Telnet connection is not possible until an IP address has been configured and a Telnet password has been configured.
Understand the boot sequence of a router.
When you first bring up a Cisco router, it will run a power-on self-test (POST), and if that passes, it will look for and load the Cisco IOS from flash memory, if a file is present. The IOS then proceeds to load and looks for a valid configuration in NVRAM called the startup-config. If no file is present in NVRAM, the router will go into setup mode.
Describe the use of setup mode.
Setup mode is automatically started if a router boots and no startup-config is in NVRAM. You can also bring up setup mode by typing setup from privileged mode. Setup provides a minimum amount of configuration in an easy format for someone who does not understand how to configure a Cisco router from the command line.
Differentiate user, privileged, and global configuration modes, both visually and from a command capabilities perspective.
User mode, indicated by the routername> prompt, provides a command-line interface with very few available commands by default. User mode does not allow the configuration to be viewed or changed. Privileged mode, indicated by the routername# prompt, allows a user to both view and change the configuration of a router. You can enter privileged mode by typing the command enable and entering the enable password or enable secret password, if set. Global configuration mode, indicated by the routername(config)# prompt, allows configuration changes to be made that apply to the entire router (as opposed to a configuration change that might affect only one interface, for example).
What are the additional prompts available in other modes and describe their use.
Additional modes are reached via the global configuration prompt, routername(config)#, and their prompts include interface, router(config-if)#, for making interface settings; line configuration mode, router(config-line)#, used to set passwords and make other settings to various connection methods; and routing protocol modes for various routing protocols; router(config-router)#, used to enable and configure routing protocols.
Identify the information provided by the show version command.
The show version command will provide basic configuration for the system hardware as well as the software version, the names and sources of configuration files, the configuration register setting, and the boot images.
Set the hostname of a router.
The command sequence to set the hostname of a router is as follows:
enable
config t
hostname Todd
Differentiate the enable password and enable secret password.
Both of these passwords are used to gain access into privileged mode. However, the enable secret password is newer and is always encrypted by default. Also, if you set the enable password and then set the enable secret, only the enable secret will be used.
Describe the configuration and use of banners
Banners provide information to users accessing the device and can be displayed at various login prompts. They are configured with the banner command( banner MOTD/login/exec ___) and a keyword describing the specific type of banner. In configuration mode.
Set the enable secret on a router.
To set the enable secret, you use the global config command ‘enable secret’. Do not use ‘enable secret password password’ or you will set your password to ‘password password’. Here is an example:
enable
config t
enable secret todd
Set the console password on a router
To set the console password, use the following sequence:
enable config t line console 0 password todd login
Set the Telnet password on a router.
To set the Telnet password, the sequence is as follows:
enable config t line vty 0 4 password todd login
Describe the advantages of using Secure Shell and list its requirements.
Secure Shell (SSH) uses encrypted keys to send data so that usernames and passwords are not sent in the clear. It requires that a hostname and domain name be configured and that encryption keys be generated.
An encryption key is typically a random string of bits generated specifically to scramble and unscramble data. Encryption keys are created with algorithms designed to ensure that each key is unique and unpredictable.
Describe the process of preparing an interface for use
To use an interface, you must configure it with an IP address and subnet mask in the same subnet of the hosts that will be connecting to the switch that is connected to that interface. It also must be enabled with the ‘no shutdown’ command. A serial interface that is connected back to back with another router serial interface must also be configured with a clock rate on the DCE end of the serial cable.
ex.)
int f0/0
ip address 172.16.10.2 255.255.255.0
no shutdown
Understand how to troubleshoot a serial link problem.
If you type ‘show interface serial 0/0’ and see “down, line protocol is down”, this will be considered a Physical layer problem. If you see it as “up, line protocol is down”, then you have a Data Link layer problem.
Understand how to verify your router with the ‘show interfaces’ command
If you type ‘show interfaces’, you can view the statistics for the interfaces on the router, verify whether the interfaces are shut down, and see the IP address of each interface.
Describe how to view, edit, delete, and save a configuration.
The ‘show running-config’ command is used to view the current configuration being used by the router. The ‘show startup-config’ command displays the last configuration that was saved and is the one that will be used at next startup. The ‘copy running-config startup-config’ command is used to save changes made to the running configuration in NVRAM. The ‘erase startup-config’ command deletes the saved configuration and will result in the invocation of the setup menu when the router is rebooted because there will be no configuration present.
Difference between auxiliary port and console port
The main difference between the console and auxiliary ports is that the auxiliary port supports hardware flow control and the console port does not. Flow control paces the transmission of data between a sending device and a receiving device. Flow control ensures that the receiving device can absorb the data sent to it before the sending device sends more. When the buffers on the receiving device are full, a message is sent to the sending device to suspend transmission until the data in the buffers has been processed. Because the auxiliary port supports flow control, it is ideally suited for use with the high-speed transmissions of a modem. Console terminals send data at slower speeds than modems; therefore, the console port is ideally suited for use with console terminals.
