03 - Performance of Networks

 1. You've probably heard people complain about the network being slow. Nothing can be done about network performance.



 2. Many factors directly impact how fast application queries and responses will flow through the network. Which in the list is NOT a factor?
1. Network Latency 
2. Network congestion 
3. Client or Server health

  Just #3 Client or Server Health

  Just #1 - Network Latency

  All of the items in the list are potential factors in network performance

  None of these are factors

 3. Bandwidth is a big factor in network performance. What is network bandwidth?

  The bandwidth is simply referring to the speed that the internet travels to one's home network

  The bandwidth describes how much data can be transferred over a connection in a given time.

  The bandwidth describes how big each band holding every network cable can be.

  The bandwidth describes the width of each 'band' (cable) that connects to each client computer

 4. In the 'olden days' a non-broadband dial up modem had a bandwidth of ….

  256 Mbps


  A dial-up modem would not have any bandwidth at all


 5. Basic copper wire based broadband (download bandwidth) has a bandwidth of:



  256 Mbps

  2 to 10 Mbps

 6. Read the excerpt below that provides additional descriptions and see if you can fill in the blanks.
Fibre Optic Broadband has a bandwidth of 10 to 75 Mpbs; 
Ethernet wired network using Cat-5 cable  has a bandwidth 
of 10 - 100 Mbps. Ethernet wired network using Cat-6 cable
(you'll learn about this in network hardware) 
has an ____________ bandwidth of ________________

  There is no such thing as Cat-6 so this question cannot be answered.

  decreased / 10Mbps to 100Mbps

  infinite / infinite

  increase / 1 Gpbs to 10 Gpbs

 7. Compared to all the descriptions and networks you've explored, what do you think the bandwidth of a wi-fi network would be?

  54 - 150 Gbps with Fast Wi-Fi up to 900 Gpbs

  54 - 150 Mbps with Fast Wi-Fi up to 900 Mpbs

  1 - 10 Mbps with Fast Wi-Fi up to 90 Mpbs

  1 - 20 Tbps with Fast Wi-Fi up to 999 Tpbs

 8. Chosing a network is a matter of balancing cost and performance because …

  the higher the bandwidth, (usually) the more expensive it is

  The higher the bandwidth the lower the performance of the network.

  The lower the bandwidth the greater the cost

  the higher the bandwidth the cheaper it is

 9. It is possible for even the most impressive network to slow down if enough people are using it at the same time.



 10. The "contention ratio" is ….

  The ratio of users compared to available bandwidth

  The ratio of bandwidth to speed

  The ratio of speed to bits in a network.

  The ratio of users compared to the no. of computers

 11. Assume all your neighbors are home and surfing the net on Sunday evening and most people are asleep on Monday morning 2am. When would the internet seem most responsive?

  It would fail to work at all on Sunday evening.

  It would be equally responsible on both Sunday evening and Monday morning

  Sunday Evening

  On Monday morning

 12. If you were a big business that absolutely needed a reliable and fast internet connection - what could you do?

  pay extra money for a high-contention ration connection

  pay less money so that their bandwidth is increased

  install bigger cables underneath the ground to increase the bandwidth manually

  pay extra money for a low-contention ratio connection

 13. A contention ration of 100: 1 would mean that…

  This is not a valid ratio as it cannot be explained.

  100 lines could be being used by 100 users

  100 users may be sharing 1 line at any given time

  1 user could be using a 100 lines at any given time

 14. A 1:1 ratio would mean that only a single connection is allowed on the line. This would guarantee a constant speed at all times!



 15. Wired networks will use Ethernet (copper) cables to carry data. They come in two main categories.

  Cat-5(faster), Cat-6(slower)

  Cat-1 and Mat-1

  Bat-1 (super fast) and Cat-2(medium level speed)

  Cat-5(slower), Cat-6(faster)

 16. Fibre optic cable transfers data using light and is super fast - in fact the bandwidth is only limited by…

  The strength of the sun (light source) on that particular day

  the cable itself

  The speed of light.

  the equipment connected to it rather than the cable itself

 17. Wi-fi is considered a radio technology and so its performance is affected by factor that affect radio. One of these factors is:

  Choice of cable strength

  Choice of Yap (a type of radio signal)

  Choice of colour (of the wifi radio)

  Choice of Band

 18. Read the excerpt below and fill in the blanks:
Wi-Fi works in two frequency bands - one at 2.4GHz and another at 5Ghz.
A 'band' is a range of frequencies. These bands are further divided into separate 
"channels" Using separate channels is a good idea in terms of improving network 
performance because ..................................? Note: The 2.4 GHz band 
can carry several non-overlapping channels. The 5Ghz band carries many non-overlapping
channels and so has a higher capacity, but the equipment is more expensive and it has
a shorter range.

The exact number of channels is regulated by law. 

  it reduces the signal strength which is helpful for security and performance.

  it improves performance by increasing the wi-fi signal by 1000 times

  it increases the interference caused by devices which improves performance

  it reduces the interference caused by nearby devices

 19. In addition to the choice of band and channel which other factors from the list can affect Wi-fi network performance?
1. Radio Interference 
2. No of Radio devices in any given country 
3. Blockage by walls (thick walls and floors) 
4. Limited connections available to users. 

  All of the listed items

  1 only


  1 and 2

 20. Fill in the blanks
Another factor in measuring network performance is how many data errors 
happen over a given time. You can think of an "error" in this regard as 
the situation caused by a binary '1' being sent; but a binary '0' 
being actually received on the other end. (or the other way round). 

There are two main reasons for this happening 

1. Heat (the weather being too hot) or Cold (extreme cold) and


  Heavy duty nuclear weaponry and dust and fire attacks

  Light rain or drizzling

  Hackers that specialise in inverting bits and Extra bright sunshine

  Interference (electric motors or power equipment) can make bits flip randomly and weak signal strength

 21. Generally speaking, the longer the cable (the length of the cable)….the -

  weaker the radio signal

  stronger the signal

  weaker the signal

  greater the performance

 22. "Latency" is a word you will hear a lot when dealing with networks. It is the technical word for…….





 23. "Latency" is much more of an issue (in terms of how far a bit has to travel) in LANS.



 24. In a huge network, every switch, router and cable would add (delay) latency to the connection.



 25. A high performance network should have high latency.