Network Troubleshooting and Tools

Question 1

Which should you do during the process of identifying the problem?

Duplicate the problem

Establish a plan of action

Question users

Create a hypothesis

Answer 1

Duplicate the problem

Question users

During the identification of a problem, you should question users and try to duplicate the problem

Question 2

Which technique is used to determine the root cause of a problem, in which you split a system into smaller subprocesses for examination?

Top-to-bottom OSI analysis

Divide and conquer analysis

Bottom-to-top OSI analysis

Answer 2

Divide and conquer analysis

The divide and conquer analysis technique is used to divide complex processes into small subprocesses that are easier to analyze

Question 3

What is the next step in problem solving once a theory is confirmed?

Create a hypothesis

Consider multiple approaches

Establish a plan of action

Answer 3

Establish a plan of action

After a theory or hypothesis is confirmed, you should establish a plan of action to resolve the problem

Question 4

hat is the final step in resolving a problem?

Implement a solution

Validate a theory

Document

Answer 4

Document

The documentation of the finding, actions, and outcomes is the final step in the resolution of a problem. It allows us to solve future problems more quickly

Question 5

Which tool is used to troubleshoot wiring breaks in network cabling?

OTDR

Tone generator

TDR

Answer 5

TDR

A time domain reflectometer is a tool that sends electronic pulses of energy down a wire and reads the time their reflection comes back. A calculation is made to determine the length of the cable

Question 6

You need to find a network cable that is not labeled on a wiring panel; which tool should you use to identify the cable?

Cable tester

Tone generator

TDR

Answer 6

Tone generator

A tone generator is used in conjunction with a tracing probe to identify network cables. It operates by injecting a warbling tone into the cable so that the tracing probe can amplify the signal audibly

Question 7

You are working alone and want to test a fiber-optic cable. Which tool will help you test the fiber-optic cable quickly?

TDR

Light meter

Loopback adapter

Answer 7

Loopback adapter

Although you could use a light meter to test the fiber-optic cable, you would need to move the source over to the other fiber strand. A loopback adapter will allow you to test the cable with one test of both strands

Question 8

Which software tool will allow you check if a web application running on a server is online?

nslookup

tracert/traceroute

Port scanner

Answer 8

Port scanner

A port scanner will allow you to check if an application is accepting connections. The port will return an open status, and most port scanners will check for an HTTP response. The ping utility will only check if the server is online

Question 9

You believe there is problem upstream of your Internet connection and want to gather information to provide the ISP. Which tool will you use to gather statistics?

tracert/traceroute

pathping

nslookup

Answer 9

pathping

The pathping tool will perform a traceroute to the destination address. It will then check each hop with a number of ICMP packets and return statistics on each hop

Question 10

Which tool allows examination at the packet level for traffic from an application?

Protocol analyzer

dig

Spectrum analyzer

Answer 10

Protocol analyzer

A protocol analyzer will allow us to inspect packet levels of traffic that is captured from an application

Question 11

You need to check the configured MTU on the interface of a Linux host; which command should you use?

ipconfig

ifconfig

mtuconfig

Answer 11

ifconfig

The ifconfig command will allow you to inspect the MTU on the interface of a Linux host. It will also allow you to change the MTU temporarily

Question 12

You need to check the port an application is listening on; which command should you use to view the information?

portqry

ifconfig

netstat

Answer 12

netstat

The netstat command will allow you to see layer 4 binding between applications and the TCP/UDP ports. On Windows, the netstat -ab command will display listening ports. On Linux/Unix, the netstat -ap command will perform the same function

Question 13

You need to analyze whether an application is responding to a client request; which command will allow you to capture the traffic?

tcpdump

nmap

portqry

Answer 13

tcpdump

The tcpdump command will allow packet capture of an interface. When run on the server the application is responding on, tcpdump can capture the response of the application for further analysis

Question 14

Which command will allow you to clear the cached MAC addresses on a host?

arp -g *

ipconfig /flushdns

arp -d *

Answer 14

arp -d *

The arp command allows you to manipulate the MAC address cache of a host. When you issue the arp -d * command, you will clear all MAC address entries in the ARP cache

Question 15

Which describes what happens to a wireless signal as it moves further away from the source?

Increased latency

Increased jitter

Increased attenuation

Answer 15

Increased attenuation

The attenuation of the signal increases as the signal moves further away from the source. Attenuation is the gradual absorption of a signal’s energy in the air

Question 16

You believe there is a break in a fiber-optic cable that spans 5 miles; which tool will help you determine where the cable break cable is?

TDR

OTDR

Cable tester

Answer 16

OTDR

An optical time-domain reflectometer (OTDR) sends a pulse of light down the fiber-optic cable and measures the time and reflection strength. This measurement will determine where a break occurs in the fiber-optic cable

Question 17

Which Nmap scan will send an URG, PSH, and FIN flag to trick the operating system to respond with an RST?

Xmas-tree scan

Fin scan

Null scan

Answer 17

Xmas-tree scan

The Xmas-tree scan will send the URG, PSH, and FIN flags in the TCP header to trick the operating system into sending back an RST for closed ports

Question 18

As routers, switches, and NAT processes are added to a routed switch path, what happens?

Latency increases

Jitter increases

Latency decreases

Answer 18

Latency increases

Latency is the measurement of delay between the source and destination. As components such as switches, routers, and NAT processes are added, latency is increased because of the lookups and forwarding

Question 19

Which term describes the phenomenon of a wireless signal changing in frequency as it passes through different materials?

Reflection

Attenuation

Refraction

Answer 19

Refraction

As a wireless signal passes through different materials, the signal will slow down and change in frequency. This phenomenon is called refraction, similar to a prism and light

Question 20

You find that a workstation has no connectivity to the network. When you use ipconfig, the IP address reports as 169.254.34.22 with a subnet mask of 255.255.0.0. What is the possible problem?

The subnet mask is incorrect.

The IP address is on the wrong subnet.

The original IP address has expired.

Answer 20

The original IP address has expired.

The 169.254.x.x prefix is an Automatic Private IP Addressing (APIPA) IP address, also called a link local address. The presence of this address means that either the original DHCP address has expired or the DHCP server is unavailable

Question 21

You believe that packets are being routed via the wrong gateway; which tool will allow you to verify the route a packet takes to the destination IP address?

route print

tracert

ipconfig

Answer 21

tracert

The tracert command will allow you to see the path an IP packet takes to the destination. The Linux/Unix command is traceroute

Question 22

You are diagnosing a wireless issue and you believe that the problem is related to RF noise. Which measurement should you focus on to prove your theory?

RSSI

SNR

dB strength

Answer 22

SNR

Wireless access point (WAP) diagnostics and spectrum analyzers will display RSSI and SNR. The signal-to-noise ratio is the separation of signal to floor noise measured in decibels (dB). The SNR will prove the theory of excess RF noise compared to the originating signal

Question 23

What is the outcome if you have a speed mismatch on a network connection?

High collision rate

High error rate

No link status

Answer 23

No link status

If there is a speed mismatch between the two connection devices, you will have no link status, because the carrier signal is different

Question 24

You have a high error rate on an interface and believe that crosstalk is to blame. What should be checked to prove your theory?

Network cable specifications

Duplex

Speed

Answer 24

Network cable specifications

Crosstalk happens when the electrical signals on one wire induces erroneous signals on another wire. The correct category cable specifications are defined by the Telecommunications Industry Association (TIA)

Question 25

Which command is used to verify the configuration of a host-based firewall on a Linux host?

nmap

iptables

ifconfig

Answer 25

iptables

The iptables command allows configuration and inspection of the host-based firewall in many Linux distributions