2.8 Given a scenario, use networking tools Flashcards
What do Wi-Fi analyzers do?
Wi-Fi analyzers is software that can be installed on a device
Record stats for the AP the client is connected to & detect other nearby APs
How is wireless signal strength measured?
Decibal (dB) units
What is the signal strength’s starting/reference point?
0dBM (decibal milliwatts)
This represents a signal with a power of 1 milliwatt (mW). Think of it as the baseline.
What are signal strengths weaker than the reference point represented by?
Negative numbers
i.e. -30 dBm means the signal is much weaker than 1mW, like a thousandth of a miliwatt
Why are dBm values often negative for Wi-Fi signal strength?
Wi-Fi devices abide by power regulations, limiting their signal strength
What Wi-Fi signal strength is considered good?
-65 dBm or larger
-65 dBm to 0 dBm
What may happen if the Wi-Fi signal strength is over -80 dBm?
Likely to suffer from packet loss or be dropped
What does dB’s logarithmic scale mean?
A small change in value significantly alters performance
i.e. If you have a signal and you increase its strength by +3 dB, you are doubling the signal’s power. Conversely, if you decrease its strength by -3 dB, you are halving the signal’s power.
What is compared in the Signal-to-Noise Ratio (SNR)?
Data signal strength to background noise in wireless environment
i.e. with a signal at -65 dBm and noise at -90 dBm, the SNR is 25 dB. However, if the noise increases to -80 dBm, the SNR drops to 15 dB, significantly degrading the connection
What does Signal-to-Noise Ratio (SNR) indicate?
How much stronger the data signal is compared to the noise
the background noise in the wireless environment
How is background noise in wireless environments measured?
dBm (decibel milliwatts)
What does a larger dBm imply for wireless background noise?
(dBm values closer to 0)
Higher levels of noise
What does a higher SNR value indicate?
(Signal-to-Noise Ratio)
Stronger signal relative to background noise
This results in good network performance
What does a lower SNR value indicate?
(Signal-to-Noise Ratio)
Weaker signal relative to background noise
This can lead to degraded performance or connectivity issues
What is SNR (Signal-to-Noise Ratio) measured in?
dB (decibels)
What does each computer connect to in a structured cabling system?
Wall port using a patch cord
What is behind a wall port in a structured cabling system?
Permanent cable routed to an equipment room, connected to a patch panel
The permanent cable is routed through the wall & ceiling
The patch panel is then connected to a switch
What are permanent cables terminated to in a structured cabling system?
Patch panels via punchdown blocks
Punchdown blocks are referred to as Insulation Displacement Connectors (IDC)
Purpose of a Cable stripper?
To remove the outer jacket from a cable
This exposes the intter wires for termination or splicing
Adjust the stripper to the correct diameter, then insert the cable and rotate the tool once or twice. This creates a score cut in the insulation, allowing you to remove the jacket
Why are electrician snips needed when terminating Cat 6/6A cables?
They have a plastic star filler running through it
This keeps the pairs separated
There’s also a nylon thread called a “ripcord” that can be pulled down the jacket to open it up further if any wire pairs are damaged initially. Trim any excess ripcord before terminating the cable.
Purpose of a punchdown tool?
To fix each conductor into an IDC
(IDC = Insulation Displacement Connector) (aka Punchdown block)
Untwist wire pairs, place them in color-coded terminals in the IDC, follow T568A or T568B order. Keep untwisting to 1/2”. Press wires into terminals with punchdown tool; blades cut insulation for contact
Insert wire pairs into RJ45 plug according to T568A or T568B. Place plug in crimper tool, close tightly to pierce insulation at pins and seal to outer jacket.
Purpose of a cable tester?
Verifies integrity & accuracy of network cable connections
What does an LED indicate in a cable tester?
Successful termination
What does it mean if an LED does not activate when using a cable tester?
The wire is not conducting a signal
Typically because the insulation is damaged or the wire isn’t properly inserted into the plug or IDC
What does it mean if the LEDs in a cable tester do not activate in the same sequence at each end?
The wires have been terminated to different pins at each end
Use the same type of termination on both ends
Purpose of a Toner probe?
Identify a cable from within a bundle
Many cable testers also incorporate this function
Purpose of a loopback plug?
Test an NIC or switch port
When should you see when you connect a loopback plug?
LED showing that the port can send & receive
Purpose of a network tap?
To intercept & forward signals passing over a cable to a packet/protocol analyzer
How does a passive network tap differ from an active one?
Having a splitter to copy signals to a monitor port
How does a active network tap differ from a passive one?
Performing signal regeneration
Signal regeneration is the process of amplifying and restoring degraded signals to their original strength and quality along a communication path
What signaling over copper wire is too complex for a passive tap to monitor?
Gigabit signaling
What can be affected by a passive network tap’s optical splitting?
Some types of fiber links
What does it mean that pasive network taps make no logic decisions?
Monitor port receives every frame & the copying is unaffected by load
even when there is a high volume of network traffic passing through, the process of copying the signals to the monitor port remains consistent and unaffected.
2 ways to implement network sniffing?
- Network tap
- Switch’s SPAN/mirror port
In a SPAN/mirror port, a sensor is linked to a port on a switch set to copy the traffic from chosen access ports or all others. This lets the sensor analyze network frames without disrupting regular traffic flow.
