Topic 9.3.1 The Internet

Question 1

Explain the structure of the internet

Answer 1

A network of interconnected computer networks which uses end-to-end communication protocol
It is a wired network, cables pass under oceans connecting to different continents

Question 2

Explain Internet Service Providers (ISP)

Answer 2

A company that provides customers with access to the internet
Nation ISPs provide internet to Regional ISPs then customers buy internet from the Regional ISPs

Question 3

Define a packet

Answer 3

A container of data being transmitted over networks.
Labelled with addresses for sender and recipients.

Question 4

Explain packet switching

Answer 4

This is a network where data is sent in packets.
Each message is split up into multiple packed and sent to the recipient via the best possible route using dijkstras algorithm.
Recipient will reassemble the packets together

Question 5

Explain the role of routers in data transmission

Answer 5

When packets are being transmitted, they will pass through a number of routers in order to get to the intended recipient .
Routers use the recipient’s address found inthe header of the packet to know where to send the packet next.

Question 6

Explain the process of ‘hops’ and Time To Live (TTL) in data transmission

Answer 6

Each time a packet passes through a router, a “hop” is said to occur
Every packet has a limit on the number of hops it can perform, this is the TTL
If a packet reaches its TTL, the packet is deleted and transmitted again.

Question 7

What are the components of a packet and their purposes

Answer 7

Sender’s Address -
Where packet has been sent from and where responses will be sent to

Receivers Address -
Where packet is being sent to, helps routers direct it to correct location

Packet Contents -
Data that is being transferred

TTL -
Max number of hops that can be performed

Sequence Number -
Knows the number of packets in a message and which position this packet will be in. Allows packets to be reassembled.

Question 8

Define a Router and its purpose

Answer 8

They allow packets to reach their destinations, by connecting different networks.

They send packets via the fastest possible route (dijkstra). Either least hops or least congestion.

Question 9

Define a Gateway and its purpose

Answer 9

Allows packets to reach their destinations by connecting different networks

Gateways strip away most details of the packet leaving just the data being transmitted.

Done when two networks use different protocols so the packet must change to conform to both protocols.

Gateway will give the packets new sender and receiver addresses which will comply to the new protocol

Question 10

Where will routers and gateways be used

Answer 10

Routers -
Homes, Offices
Also can create local networks of devices

Gateways -
Used when 2 different networks operate using 2 different protocols (one uses SMTP and an older network uses X.400 an older protocol for older devices)
So gateways translate HTTPS into the older protocol so it can be understood and both protocols can communicate effectively

Question 11

Explain Routing Tables

Answer 11

Routers have tables (Routing Tables) which is a list of all the possible and fastest paths in a network.
These tables are frequently updated to ensure maximum performance

Question 12

What is internetworking

Answer 12

The process of connecting multiple networks so data can be transmitted between them

Question 13

Define a URL

Answer 13

An address used to access webpages on the internet or in a network.

Question 14

How does a URL work in terms of internetworking

Answer 14

They are a method of accessing resources across the internet

Question 15

Explain Fully Qualified Domain Names (FQDN)

Answer 15

Specifies an exact resource on a webpage.
FQDN - www.bbc.com.
DN - bbc.com

Question 16

Explain Domain names

Answer 16

Identifies a webpage on the internet.
Domain names provide a human-friendly interface of an IP address.

Question 17

Explain IP addresses

Answer 17

IP means Internet Protocol.
Every device with access to a network or the internet will have an IP address.

Question 18

How are domain names organised

Answer 18

Via subdomains
These are additional parts of a domain name that allows the domain owner to organise different sections of their website under the same main domain

for example:
support.google.com
mail.google.com
drive.google.com

Support, mail and drive are all subdomains, hosting different applications under the same domain ‘google’

Question 19

What is the purpose of the domain service

Answer 19

Providing a human interface for an IP Address making it easy for humans to access websites and services.
It relies upon the Domain Name System (DNS)

Question 20

What is a Domain Name Server (DNS)

Answer 20

Specialised servers that store and manage the DNS records needed for obtaining the IP address of webpages.

Question 21

How does a Domain Service work in relation with the Domain Name Server (DNS)

Answer 21

When a user enters a domain name (website),
the query is sent to the DNS servers to find the corresponding IP address of the website.

Since DNS servers store IP addresses in their cache when they are used, the more popular a website is, the quicker it will take to find the website.

If a DNS server doesn’t have a record of the domain (website), it will send the request to another DNS server. So if a website is rarely visited it will pass through many DNS servers to try and find it, meaning it will be slightly slower to access.

Question 22

Explain the purpose of an Internet Registry

Answer 22

An organisation responsible for the allocation for allocating IP addresses.
To protect the depleting number of unallocated IP addresses.
There are only five Internet Registries in the world.

Question 23

Why are Internet Registries needed

Answer 23

Manage international internet resources (IP Addresses)
They prevent conflicts over which IP address belongs to who.
Prevents wastage of IP addresses as they are scarce