3.1 The Internet Flashcards
What is the internet?
The internet is a collection of inter-connected networks
What is the world wide web?
- One service that makes use of the internet. It is accessed from a browser and HTTP to send or receive data
- It is accessed from a web browser such as Chrome, Safari, Edge or Firefox
- It makes use of HTTP to send and receive data
What is a wide area network?
- Using recourses supplied from a ‘third party carrier’ and have a number of geographical locations
- A WAN uses cables, telephone lines, satellites or radio waves to connect two or more remote locations
- The internet is the largest WAN in the world
Give some examples of organisations which could have WANS
- Universities
- Schools
- Large companies
- Governments
- Research organisations
What is the Internet of Things (IoT)?
Devices such as mobiles, parking metres etc. In 2020, over 31 billion IoT items connected to the interenet
What is an IPv4 address?
An internet protocol which is represented by 4 8-bit numbers (0-255) separated by dots, for example 72.129.214.16
What is an IPv6 address?
128-bit numbers represented in hex
What is circuit switching?
A dedicated connection between 2 clients
How does packet switching solve circuit switching in a large network?
It uses multiple connections and routers to send it to the right destination
What is packet switching?
Each file is broken up into data ‘packets’ of 512 bytes, and each file is given headers
What “meta data” is in each packet?
- The IP address it is going to
- The IP address it has come from
- The sequence number of the packet
- The number of packets in the whole communication
- Error checking data
Why may packets go and take different routes?
A router may decide which path is better, faster and safer to go through
How do packets come back in the same order and still have the same data?
- The client re-orders the packets into the correct order
- Corrupt packets are requested to be resent etc.
Nodes
Points on a network digram
What do routers do?
Routers are nodes that can routes packets from one place to another
What is a Domain Name System (DNS)?
A domain name is a name used to refer to an IP address. A DNS server translates a web address (URL) into an IP address.
What are DNS root servers?
13 database servers which contain a complete database of all domain names and IP addresses.
What happens if a DNS server receives a request and data is not in its database?
It will pass the request on to another server until it reaches one with the matching name and IP address. ISP’s are owned by lower level DNS servers
Why might your IP address change?
The IP address is the one that belongs to your router that you are connected to.
What is dynamic IP address?
When a router retries to connect to the internet, it may receive a new IP address
What is a Network Interface Card (NIC)?
A card that connects to a modem (router)
What is MAC (Media Access Control) addressing?
A unique MAC address assigned to a device (2 ^ 48 possible mac adresses)
What is the role of a MAC address?
A router uses a MAC address of the next router to send the data packet on the next leg of it’s journey
WAN
Wide Area Network
Packet
One unit of data sent through an IP address
Routing
Directing IP packets to their destinations
DNS
Domain Name System
IP address
Internet Protocol Address. Where packets of data are sent to or received from
MAC address
Media Access Control address. The unique identifier of each device
