Chapter 7 - Notes

Question 1

Show how the 4 bit digital value of 0110 is converted to analog signal by a modem that modulates the amplitude of a carrier wave:

Answer 1

Short Amplitudes = 0
Long Amplitudes = 1

Question 2

Consider an uncompressed 1200 x 780 image with each pixel stored using an 8 bit grayscale representation in under 1 second, what is the minimum acceptable transmission speed?

Answer 2

A = (1200 x 7800) pixels per image
B = 8 bit/pixel per sec
S = (A x B) bps
Using dimensional analysis, the answer is 7.488 Mbps

Question 3

How long would it take to transmit that 1200 x 780 image using a 1 gigabit ethernet network?

Answer 3

We know Bandwidth = bits/sec = bits/time

and So:

1 Gbps = 7.488 Mbps (from previous question)
1 Gbps = 7.488 Mb/t
1 Gb 1000 Mb = 7.488 Mb/t
s Gb
t = 7.488 s = 7.488ms
1000

Question 4

How long would it take to transmit that 1200 x 780 image using a 802.11g WiFi Connection (54 Mbps)?

Answer 4

bandwidth = bits/sec

54 Mb/s = 7.488Mbs
54 Mb/s = 7.488Mb/t
t = 7.488Mb/54 Mb/s
t ​= 0.1386 s

Question 5

Where did the idea of Bluetooth originate from?

Answer 5

From Harald “Bluetooth” Gormsson, who united Denmark and Christianized the Danes

Question 6

Which topology would be disrupted if the Central Node was down?

Answer 6

Star Topology

Question 7

Which topology does “Ethernet Lan with Shared Cable” have?

Answer 7

Bus

Question 8

What security issues could arise from the use of an ethernet-like bus topology to implement a LAN?

Answer 8

Everyone has access to the same line of communication, so it everyone would see the same message. You would need to use a packet sniffer/analyzer to adjust.

Question 9

The overall Structure of the Internet is a combination of:

Answer 9

LAN and WAN

Question 10

Internet service with greater than 256K is called:

Answer 10

Broadband

Question 11

True or False: A WiFi hot spot is where computers can connect to the internet through a nearby wireless station to a network

Answer 11

True (Except for Cell Phones)

Question 12

Do users need a ISP to access a Lan?

Answer 12

No

Question 13

Name 3 Common Topologies for LANs

Answer 13

Star, Bus, Ring

Question 14

Most WANs use ___ technology to transmit message:

Answer 14

Store and forward (or packet switched)

Question 15

What is a protocol?

Answer 15

A standard set of rules

Question 16

What are the Seven Layers of OSI?

Answer 16

1. Physical Layer
2. Data Link Layer
3. Network Layer
4. Transport Layer
5. Session Layer
6. Presentation Layer
7. Application Layer

Question 17

Which OSI Layers are physically connected?

Answer 17

Physical and Data Link Layer

Question 18

Which of the 7 OSI Layers have Error Correction?

Answer 18

Data Link and Transport Layers

Question 19

Which OSI Layer uses bits?

Answer 19

Physical

Question 20

Which OSI Layer uses Frames?

Answer 20

Data Link

Question 21

Which OSI Layer(s) uses Packets?

Answer 21

Transport and Network Layers

Question 22

Which OSI Layer is a Distant Node?

Answer 22

Network Layer

Question 23

Which OSI Layer is a Distant Port?

Answer 23

Transport Layer

Question 24

Which 3 of the 7 OSI Layers make up the Application/Process Layer?

Answer 24

Application, Presentation and Session Layers

Question 25

Nodes A & B are exchanging messages using the ARQ algorithm. State which action node B should take?

Node A Node B

M(3) ->

<- ACK(3)

M(3) ->

Answer 25

Node A Node B

M(3) ->

<- ACK(3)

M(3) ->
<- ACK(3)

Question 26

The main task of the network layer is to:

Answer 26

Handle delivery of communication across network of computers, including addressing schemes and routing

Question 27

True or False: Medium Access Control protocols manage the physical layers, how bits are transmitted over different kinds of wires

Answer 27

False, Physical would.

Question 28

True or False: A DNS Server translates urls into address on the web.

Answer 28

False: Protocol-Host-Port-Page, it only translates the host name