Exam Essentials

Question 1

What is Bootstrap?

Answer 1

Stored in the microcode of the ROM, the bootstrap is used to bring a router up during initialization. It boots the router up and then loads the IOS.

Microcode is stored in the ROM or in the erasable programmable ROM (EPROM) and cannot easily be modified by generic programmers.

Question 2

POST (power on self-test)

Answer 2

Stored in the microcode of the ROM, the POST is a diagnostic testing sequence that runs to check the basic functionality of the router hardware(computer keyboard, random access memory, disk drives, and other hardware are working correctly) and determines which interfaces are present

Question 3

ROM monitor

Answer 3

Stored in the microcode of the ROM, the ROM monitor is used for manufacturing, testing, and troubleshooting, as well as running a mini-IOS when the IOS in flash fails to load.

Question 4

Mini-IOS

Answer 4

Called the RXBOOT or bootloader by Cisco, the mini IOS is a small IOS in ROM that can be used to bring up an interface and load a Cisco IOS into flash memory. The mini-IOS can also perform a few other maintenance operations.

Mini-IOS is a fallback utility that contains a stripped down version of IOS. This is used in critical situations where IOS image in flash is not found. Mini-IOS contains only IP code that allows you to load IOS from other resources such as TFTP Server.

Question 5

Configuration register

Answer 5

Used to control how the router boots up. This value can be found as the last line of the show version command output and by default is set to 0x2102, which tells the router to load the IOS from flash memory as well as to load the configuration from NVRAM.

Question 6

What is syslog for?

Answer 6

Syslog allows you to display, sort, and even search messages, all of which makes it a really great troubleshooting tool. The search feature is especially powerful because you can use keywords and even severity levels. Plus, the server can email admins based on the severity level of the message.

Question 7

The popular ways to gather syslog messages from Cisco devices?

Answer 7

Logging buffer(RAM inside router or switch) [on by default]

Console line[on by default]

Terminal lines [using the ‘terminal monitor’ command]

Syslog server

Question 8

The system message format parts

Answer 8

seq no This stamp logs messages with a sequence number, but not by default. If you want this output, you’ve got to configure it.

Timestamp Data and time of the message or event, which again will show up only if configured.

Facility The facility to which the message refers.

Severity A single-digit code from 0 to 7 that indicates the severity of the message.

MNEMONIC Text string that uniquely describes the message.

Description Text string containing detailed information about the event being reported.

Question 9

What are the seven severity levels for syslog

Answer 9

Emergency (severity 0) System is unusable.

Alert (severity 1) Immediate action is needed.

Critical (severity 2) Critical condition.

Error (severity 3) Error condition.

Warning (severity 4) Warning condition.

Notification (severity 5) Normal but significant condition.

Informational (severity 6) Normal information message.

Debugging (severity 7) Debugging message

Question 10

How to change severity level and enable/disable defaults of sending log messages

Answer 10

Router(config)#logging console ‘severity’
Router(config)#logging buffered ‘severity’

to disable:
no logging console
no logging buffered

Question 11

What is NTP?

Answer 11

Network Time Protocol provides pretty much what it describes: time to all your network devices. To be more precise, NTP synchronizes clocks of computer systems over packet-switched, variable-latency data networks.

Question 12

What are CDP and LLDP for?

Answer 12

Cisco Discovery Protocol (CDP) is a proprietary Layer 2 protocol designed by Cisco to help administrators collect information about locally attached Cisco devices. Armed with CDP, you can gather hardware and protocol information about neighbor devices, which is crucial information to have when troubleshooting and documenting the network. Another dynamic discovery protocol is Link Layer Discovery Protocol (LLDP), but instead of being proprietary like CDP, it is vendor independent.

Question 13

What information is provided in the ‘show cdp neighbors’ command?

Answer 13

Displays brief information about directly connected devices. device ID, local interface, holdtime, capability, platform, and port ID (remote interface).

Question 14

What is device ID?

Answer 14

Hostname of connected device. If you see MAC address here, this indicates that device is not assigned a name so far.

Question 15

What is local interface?

Answer 15

The port or interface on which you are receiving the CDP packet

Question 16

What is holdtime?

Answer 16

The remaining amount of time the router will hold the information before discarding it if no more CDP packets are received

Question 17

What is Capability?

Answer 17

S stands for switch and R stands for Router. The capability of the neighbor—the router, switch, or repeater. There are a few other capability codes.

Question 18

What is platform?

Answer 18

Hardware platform of remote device. The type of Cisco device directly connected.

Question 19

What is port ID?

Answer 19

The neighbor device’s port or interface on which the CDP packets are multicast.

Question 20

Understand how to establish a Telnet session with multiple routers simultaneously.

Answer 20

If you telnet to a router or switch, you can end the connection by typing exit at any time. However, if you want to keep your connection to a remote device but still come back to your original router console, you can press the Ctrl+Shift+6 key combination, release it, and then press X.

Question 21

Identify current Telnet sessions

Answer 21

The command ‘show sessions’ will provide you with information about all the currently active sessions your router has with other routers.

Question 22

How to build a static host table? How many IP addresses can you assign to a hostname?

Answer 22

Switch(config)#ip host ‘host name’ ‘IP address’

You can assign up to eight IP addresses to a hostname

Question 23

How to verify host table on a router.

Answer 23

You can verify the host table with the ‘show hosts’ command

Question 24

How to use DNS server to resolve hostnames?

Answer 24

Switch(config)#ip domain-lookup [only if you used ‘no ip domain-lookup’ command before!]

Switch(config)#ip name-server ‘IP address’

Switch(config)#ip domain-name ‘lammle.com’

Question 25

Describe the function of the ‘ping’ command.

Answer 25

Packet Internet Groper (ping) uses ICMP echo requests and ICMP echo replies to verify an active IP address on a network.