Topic 9.3.1 The Internet Flashcards
Explain the structure of the internet
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
Explain Internet Service Providers (ISP)
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
Define a packet
A container of data being transmitted over networks.
Labelled with addresses for sender and recipients.
Explain packet switching
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
Explain the role of routers in data transmission
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.
Explain the process of ‘hops’ and Time To Live (TTL) in data transmission
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.
What are the components of a packet and their purposes
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.
Define a Router and its purpose
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.
Define a Gateway and its purpose
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
Where will routers and gateways be used
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
Explain Routing Tables
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
What is internetworking
The process of connecting multiple networks so data can be transmitted between them
Define a URL
An address used to access webpages on the internet or in a network.
How does a URL work in terms of internetworking
They are a method of accessing resources across the internet
Explain Fully Qualified Domain Names (FQDN)
Specifies an exact resource on a webpage.
FQDN - www.bbc.com.
DN - bbc.com
Explain Domain names
Identifies a webpage on the internet.
Domain names provide a human-friendly interface of an IP address.
Explain IP addresses
IP means Internet Protocol.
Every device with access to a network or the internet will have an IP address.
How are domain names organised
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’
What is the purpose of the domain service
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)
What is a Domain Name Server (DNS)
Specialised servers that store and manage the DNS records needed for obtaining the IP address of webpages.
How does a Domain Service work in relation with the Domain Name Server (DNS)
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.
Explain the purpose of an Internet Registry
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.
Why are Internet Registries needed
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
