What is the internet?
The internet is a network of networks set up to allow computers to communicate with each other globally
What is the world wide web?
• The world wide web is a collection of web pages that reside on computers connected to the internet.
How does the world wide web work?
Uses the internet as a service to communicate the information contained within these pages.
How do computers communicate?
Computers communicate with each other using networks
What is the backbone?
Main part of the internet:
• A set of dedicated connections that connect several large networks at various points on the globe
• Each of these points are then connected to other regional networks controlled by ISPs
• ISPs provide access to end users
Why does each device need to be uniquely identified?
So that data can be sent to the correct destination
How are devices on a network uniquely identified?
Devices on a network are uniquely identified via their IP address.
What does URL stand for?
Uniform Resource Locator
What is the URL?
The full address of an internet resource:
• Specifies the resource on the internet
• Including resource name, and file type, so a browser can request it from the website server.
What is the purpose of internet registrars?
Internet registrars hold records of all existing website names and details of those domains that are currently available to purchase
What are internet registries?
Five global organisations governed by ICANN, with worldwide databases that hold records of all the domain names currently issued to individuals and companies, and their details.
What is the purpose of internet registries?
- They are responsible for allocating IP addresses to specific domain names, and keep track of which addresses of a domain name is associated with an IP address as a part of a domain name system
- They work together to maintain a database of address assignments that ensure an IP is used once and all domain names are distinct
How are devices uniquely identified?
Via internet protocol addressing system, an IP address
What is an IPV4 address?
An IP address made up of four octet values ( numerical values described by 8 bits ), separated by full stops
What forms the URL?
The domain name of the source + protocol
What are DNS servers?
DNS servers are dedicated computers with an index of domain names and their corresponding IP addresses.
How does a computer communicate with a web address?
- Computer queries a DNS server for a domain name
- If the IP address a given domain name is not known it is referred to a related domain server that may know
- Server returns an IP address that the computer can use to send a message to it
What is the DNS server structure?
- 13 Root DNS servers that work together to catalogue every domain name
- Segmented into geographical groupings or levels
What is the process of resolving an IP address?
- Domain name is resolved from right to left
- Refers to local DNS, if known, IP address is returned, else it refers to root
- Root may know or knows where .uk server is
- refers to .co server
- finds website server and resolves IP address
What happens if a DNS does not have a record for a particular domain?
- Recursively handles the request so that it can eventually deliver an IP address ( or an error message “ DNS not found “ )
- Supplies client with a referral to a DNS server authoritative, and the client follows this and subsequent referrals to successively lower level DNS servers
Why must domain names be unique?
DNS request could be confused, and deliver wrong addresses.
What is an IP address?
Internet protocol address, is a unique address that is assigned to a network device.
What is the purpose of an IP address?
Indicates where a packet of data is to be sent or has been sent from
How do routers use IP addresses?
Routers use addresses to direct data packets to the correct locations.
