Exam one

Question 1

Which type of satellite has the longest delay and why

Answer 1

GeoStationary - it is the farthest away from earth

Question 2

what are 3 advantages of GeoStationary Satellites?

Answer 2

• They don’t move so coverage can be constant
• More area can be covered.
• Don’t have to have so many handoffs between satellites

Question 3

What are the advantages/disadvantages of a passive optical connection

Answer 3

Passive is cheaper than active and though it goes less distance

Question 4

What are the advantages/disadvantages of a Active optical connection

Answer 4

Active can go farther yet it is more expensive

Question 5

Why is multimode optical fiber called “multimode?”

Answer 5

You can send multiple light waves down the one cable which allows for more signals to be sent down the one strand.

Question 6

What might happen if network cabling wasn’t twisted?

Answer 6

The cable would become an antenna

Question 7

When you compute parity what are the pnumbers?

Answer 7

P1(3,5,7)
P2(3,6,7)
P3(5,6,7)

Question 8

When you check with parity if a bit was lost how do you compute parity? Pnumbers

Answer 8

P1(1,3,5,7)
P2(2,3,6,7)
P3(4,5,6,7)

Question 9

What are examples of standardization

Answer 9

train Track width

soccer fields

Question 10

What are examples of something unstandardized?

Answer 10

Air Compressor nail-gun nails

Question 11

what are the benefits of the Layering system?

Answer 11

• Each layer has a specific function and it only has to do that function.
• reduces complexity

Question 12

What are the disadvantages of the Layering system?

Answer 12

Overhead cost

Question 13

What is the difference between connectino oriented communication and connectionless communication?

Answer 13

onnection oriented communication has to establish a connection before data is transferred while connectionless does not need it before data transfer

Question 14

What is an example of a simplex system

Answer 14

A river is a simplex system

Question 15

What is an example of a half-duplex system?

Answer 15

Oil-pipeline the oil can go both directions

Question 16

List 4 things the Data Link Layer does and why each of the four are important

Answer 16

Framing –Defines when data begins and ends (how we divided data into cars)
Error Control -Checks if the data you are receiving truly is legitimate.
Flow Control - signals to the computers how fast or slow they can communicate. If multiple computers are speaking there is an algorithm they use set when to talk. Like rolling a dice and it constantly gets bigger
Local Addressing – labeling information to ensure it’s arrival to specific devices.

Question 17

4 When would you use error-correcting

Answer 17

Instant healing of the data, often uses Hamming code to correct the errors found in data. This cost more overhead so on “dangerous networks it is better to do this then to have the data sent again. (because on non-dangerous network it is easier just to get the data again at the speed of light with error-detecting.)

Question 18

When should you use error detecting?

Answer 18

Error-detecting- when you can’t fix it so you just ask to get the data again. For peaceful highways.

Question 19

computer the parity bit 01101000

Answer 19

odd

Question 20

Compute the parity bit 00011101

Answer 20

Even

Question 21

Compute the parity bit 01000110

Answer 21

Odd

Question 22

How many bit errors can hamming code self correct

Answer 22

single bit errors

Question 23

If your computer tries to send a frame out on the network and detects a collision FOUR times in a row, what are the possible wait times it will randomly choose from before trying the 5th time? (Note: This is one way the data link layer can do flow control.) What do we call this process?

Answer 23

Exponential back off Algorithm

Question 24

Public Address system Mixn match

“mr. Hawley, please report to cell 5. NOW!

Answer 24

unicast

Question 25

Public Address system mixn match

“Mr. Hawley, and those two ugly people with you…. Leave the parking log immediately”

Answer 25

Multicast

Question 26

Public Address system Mixn match

“Ok everyone, OUT OF THE POOL”

Answer 26

Broadcast

Question 27

Sometimes we insert bits into the actual data to achieve certain goals. List at least two different reasons why we would do that in the Data Link Layer?

Answer 27

Preamble—this gets the machines ready to receive data like a chorister.
Padding—This fills up the rest of the data message by filling it with zeros your computer expects the whole value and so we fill it up.

Question 28

14 If you wish to BROADCAST a message on the Data Link Layer, what should your destination address be in the Ethernet header? (in both binary and hexadecimal, please.)

Answer 28

Hexadecimals: FF-FF-FF-FF-FF-FF
Binary: 11111111-11111111-11111111-11111111-11111111-11111111

Question 29

When do you stuff a zero

Answer 29

After 5 ones we dont want to have an accidental flag!

its for Safety! 0111110

Question 30

What is bandwidth

Answer 30

How many bits it can transport

Question 31

What is latency

Answer 31

How long it takes the first bit to arrive.

Question 32

What is jitter

Answer 32

How consistent the bits are

Question 33

What is the benefit of High frequencys

Answer 33

They can hold more data, but go shorter distances

Question 34

What is the benefit of lower frequencys

Answer 34

They go farther.

Question 35

What are the three types of satellites and their uses?

Answer 35

Geo-Stationary - Tv
Low earth Orbit - spy sat.
mid earth orbit -Gps