The Bits and Bytes of Computer Networking 1

Question 1

What is a protocol?

Answer 1

A defined set of standards that computers must follow in order to communicate properly.

Question 2

What are the 5 levels of the TCP / IP Network Model? Starting from the bottom.

Answer 2

1 Physical Layer
2 Data Link Layer
3 Network Layer
4 Transport Layer
5 Application Layer

Question 3

In the OSI model, what are the 3 layers that the application layer is split into? From the bottom.

Answer 3

5 Session Layer
6 Presentation Layer
7 Application Layer

Question 4

What is the physical layer?

Answer 4

Layer 1, the physical devices that interconnect computers.

Question 5

What is the data link layer?

Answer 5

Layer 2, responsible for defining a common way of interpreting the signals that are sent over the physical layer, so that network devices can communicate.

Question 6

What is the network layer?

Answer 6

Layer 3, allows different networks to communicate with each other through routers.

Question 7

What is the transport layer?

Answer 7

Layer 4, sorts out which client and server programs are supposed to get the received data.

Question 8

What is the application layer?

Answer 8

Layer 7, the actual data being sent.

Question 9

What address is used at layer 2?

Answer 9

MAC address.

Question 10

What address is used at layer 3?

Answer 10

IP address.

Question 11

What protocol is used at layer 3?

Answer 11

Internet Protocol (IP)

Question 12

What 2 protocols are used at layer 4?

Answer 12

Transmission Control Protocol (TCP)

User Datagram Protocol (UDP)

Question 13

What are the main differences between TCP and UDP?

Answer 13

TCP = slower but very reliable.
UDP = fast but unreliable.

Question 14

What are the two types of data transfer cable at the physical layer, and how is data sent across each type?

Answer 14

Twisted copper pairs - binary is communicated across the wires as voltage changes.

Fibre optic - binary is communicated across the glass fibres by beams of light.

Question 15

What is Crosstalk?

Answer 15

On copper cables, when an electrical pulse on one wire is mistakenly detected on another wire, results in missing/ incorrect data.

Question 16

What are 2 benefits and a disadvantage of fibre optic cables?

Answer 16

Faster and longer distance transfer.
Less risk of data loss.
Expensive and fragile.

Question 17

What Layer does a hub operate on?

Answer 17

1 - Physical layer.

Question 18

What is a common issue with hubs?

Answer 18

Collision domain - As they send the information to every device on the network, can result in the electrical pulses of the various data being sent interfering with each other. Devices have to wait until network is quiet, which results in slow communications.

Question 19

Which Layer does a switch operate on, and what address does it use to send data?

Answer 19

2 - Data link layer, MAC address.

Question 20

What kind of network do hubs and switches connect devices on?

Answer 20

A LAN.

Question 21

What does a router do, and what addresses/ layer does it use?

Answer 21

Connects devices on different networks (eg home network to ISP), IP addresses, layer 3 - network layer.

Question 22

What Protocol does a router use?

Answer 22

BGP Border Gateway Protocol.

Question 23

What is modulation and line coding?

Answer 23

A way of varying the voltage of the charge moving across a cable. Line coding is when this is specifically used for computing, to communicate binary.

Question 24

What is the difference between simplex and duplex communication, and give an example of each.

Answer 24

Duplex - information flows both ways on the cable, eg, phone call.
Simplex - information only goes one direction, eg, baby monitor.

Question 25

What is Full Duplex vs half duplex?

Answer 25

Full - some pairs of wires are reserved for transmitting in each direction, communication from both ends can be simultaneous.

Half - only one device can communicate at a time.

Question 26

What is the most common kind of cable plug?

Answer 26

RJ45.