Networks

Question 1

What are the two protocols used that connect an IP address to a MAC address?

Answer 1

ARP (Address Resolution Protocol) and NDP (Neighbour Discovery Protocol)

Question 2

What is a MAC address?

Answer 2

A hardware address that is usually tied to the network interface card (NIC) in a computer (A computer’s address) - 48 bit used by ethernet

Question 3

The internet

Answer 3

a network of networks on a very large scale

Question 4

Network

Answer 4

A group of computers connected so they can communicate with each other

Question 5

Network of networks

Answer 5

Group of networks connected together so they can communicate with one another

Question 6

Heterogeneous networks

Answer 6

Different types of network (i.e. ethernet and ATM, can work together)

Question 7

Protocol

Answer 7

Describes how communication should happen

Question 8

IP address

Answer 8

Networks are given an address (just like how computers are given a MAC address). IP addresses allow you to identify which networks an address is in.

Question 9

IP address classes

Answer 9

Class A - 16.7m address per network
128.0.x.x to 191.255.x.x

Class B - 65536 addresses per network
128.0.x.x to 191.255.x.x

Class C - 256 addresses per network 1
92.0.0.x to 223.255.255.x

Class D - used for multicast
224.0.0.0 to 239.255.255.255

Class E - reserved
240.0.0.0 to 255.255.255.255

Question 10

Classless inter-domain routing

Answer 10

Aimed to slow the rapid growth of routing tables and slow IP address space

Allows a variable number of bits to be used to identify the network

Generally written as an IP address followed by the number of bits that represent the network

Question 11

IPv6

Answer 11

IPv4 address space was quickly used up

IPv6 was developed in the 90s to combat this

Uses 128 bits to represent the address - this is a huge number

Addresses usually written in hexadecimal notation

Question 12

More on IP addresses

Answer 12

Network part allocated by a standards body

Within the network, you are free to divide it up as you wish

May have smaller networks internally

Address configurations can be:

configurable - you specify the IP address (called a static IP address)

Dynamic - Computer automatically allocates an address

Question 13

circuit switch

Answer 13

a ‘circuit’ formed between two machines to allow communication

Question 14

packet switch

Answer 14

network connection broken up into smaller packets, sent interleaved with other network packets down a single set

Question 15

advantages of packet switching

Answer 15

better network utilisation due to smaller packets, less bandwidth is used

When not being sent, other computers can use the same connections to send data between them

Most networks are packet switched now

Question 16

bandwidth

Answer 16

the capacity to carry data

Question 17

Disadvantages of packet switching

Answer 17

You are not guaranteed that the packets will arrive in the same order that you send them.

You are not guaranteed that all packets will even arrive unlike a circuit switch

Question 18

OSI network layer model

Answer 18

Provides seven layers of protocols that provide increasingly higher level of abstraction of how networks work

7 - application
6 - Presentation 
5 - Session
4 - Transport 
3 - Network 
2 - Data Link
1 - Physical

Question 19

OSI - Physical

Answer 19

How the data goes over ‘the wire’, although might not be a wire e.g. fibre optic

Describes how bits get converted into electrical signals and sent

Question 20

OSI - Data link

Answer 20

How the data is formatted on the wire
Packets sent out as frames
Give details of the packet (e.g. size, who it’s for)

Question 21

OSI - Network

Answer 21

Enable packet forwarding between networks

Connectionless - the unit of transmission is a packet, have no idea that the packet sent contains information from the previously sent

Question 22

OSI - Transport

Answer 22

End to end communication - send data, arrives, handles errors

Ensures reliability

Question 23

OSI - Session

Answer 23

Managing a session between end use applications processes

Not really used in TCP/IP

Question 24

OSI - Presentation

Answer 24

How data is presented to the application e.g. HTML, CSS

Question 25

OSI - Application

Answer 25

The user interface in the OSI model

In TCP/IP , the protocols used between applications

E.g. HTTP, POP3, IMAP

Question 26

Address resolution Protocol (ARP)

Answer 26

Used to translate the IP address of the host or computer connected to a network to a MAC address on IPv4 networks

Question 27

Neighbour Discovery Protocol (NDP)

Answer 27

Used to translate the IP address of the host or computer connected to a network to a MAC address on IPv6 networks

Question 28

Domain Name System (DNS)

Answer 28

Used to convert IP addresses to humanely readable names

Distributed hierarchal system that can map names to IP (and other things)