Chapter 12 - Network Troubleshooting

Question 1

what structured troubleshooting method starts at the physical layer and physical components of the network?

Answer 1

bottom-up

Question 2

what structured troubleshooting method starts with end-user applications and moves down through OSI model

Answer 2

Top-down

Question 3

what structured troubleshooting method selects a layer based on informed guess and tests in both directions from that layer?

Answer 3

divide and conquer

Question 4

what structured troubleshooting method discovers traffic path all the way from source to destination and eliminates links and devices not relevant to troubleshooting task?

Answer 4

follow-the-path

Question 5

what structured troubleshooting method do you physically swap the problematic device with a known, working one?

Answer 5

substitution, also called swap-the-component

Question 6

what structured troubleshooting method uses educated guesses based on symptoms of the problem?

Answer 6

Educated Guess

Question 7

what structured troubleshooting method attempts to resolve problem by changing the nonoperational elements to be consistent with the working one?

Answer 7

Comparison

Question 8

what is the highest OSI layer that should be considered when troubleshooting routers and Layer 3 switches?

Answer 8

Layer 4

Question 9

three software troubleshooting tools

Answer 9

• network management system tools
• knowledge bases
• baselining tools

Question 10

what types of info does a protocol analyzer display?

Answer 10

• physical layer bit data
• data link layer info
• protocols
• description for each frame

Question 11

which hardware troubleshooting tool is used to verify that a network device is receiving power

Answer 11

Digital Multimeter

Question 12

which hardware troubleshooting tool can detect broken wires, crossed-over wiring, shorted connections and improperly paired connections

Answer 12

Cable Testers

Question 13

which hardware troubleshooting tool can be used to pinpoint the distance to a break in a cable

Answer 13

Time-domain Reflectometers.

Optical TDRs for fiber-optic cables

Question 14

which hardware troubleshooting tool used to test and certify copper and fiber cables for different services and standards

Answer 14

Cable Analyzers

Question 15

which hardware troubleshooting tool is used for troubleshooting switched networks and VLANs?

Answer 15

Portable Network Analyzers

Question 16

Where can Cisco devices send event messages to?

Answer 16

• console
• terminal line
• buffered logging
• SNMP traps
• syslog

Question 17

Cisco IOS msgs, what levels are considered Highest levels and what levels are considered Lowest levels?

Answer 17

Highest - Level 0 - 4

Lowest - Level 5 -7

Question 18

Cisco IOS command to set message levels to be logged

Answer 18

logging trap

Question 19

Which OSI layer are you troubleshooting when investigating an extended ACL related problem

Answer 19

Transport

Question 20

Which OSI layer are you troubleshooting when investigating a DNS related problem

Answer 20

Application

Question 21

Which IOS command can be used to test if other network protocols are working

Answer 21

Telnet

Question 22

what are some common symptoms of physical layer network problems?

Answer 22

• performance lower than baseline
• loss of connectivity
• network bottlenecks or congestion
• high CPU utilization rates
• console error messages

Question 23

what are some common causes of physical layer problems?

Answer 23

• power-related (fundamental reason for network failure)
• hardware faults (NICs)
• cabling faults
• attenuation
• noise
• interface config error
• exceeding design limit
• CPU overload

Question 24

symptoms of data link layer network problems

Answer 24

• no functionality or connectivity at network layer or above
• network operating below baseline performance levels
• excessive broadcasts
• console messages

Question 25

causes of data link layer network problems

Answer 25

• encapsulation errors
• address mapping errors
• framing errors
• STP failure or loops

Question 26

symptoms of network layer problems

Answer 26

• network failure

- suboptimal performance

Question 27

no single template for solving Layer 3 problems. What are the areas to explore when diagnosing problem involving routing protocols for network layer troubleshooting?

Answer 27

• general network issues
• connectivity issues
• routing table
• neighbor issues
• topology database

Question 28

transport layer troubleshooting - common improper config of ACLs

Answer 28

• selection of traffic flow
• order of ACL entries (specific to general)
• implicit deny any
• address and IPv4 wildcard mask
• selection of transport layer protocol
• src and dst ports
• use of the established keyword
• uncommon protocols (VPN and encryption protocol)

Question 29

transport layer troubleshooting - common interoperability areas when having issues with NAT

Answer 29

• BOOTP and DHCP - difficulty operating over a router running static or dynamic NAT
• DNS
• SNMP
• Tunneling and encryption protocols

Question 30

what are the application protocols to consider when troubleshooting application layer

Answer 30

• ssh/telnet
• http
• ftp
• tftp
• smpt
• pop
• snmp
• dns
• nfs