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Networking Basics :globe_with_meridians: (Domain Name System (image,…
Networking Basics :globe_with_meridians:
The Internet
The internet
: A massive network made up of computers connected all over the world.
World Wide Web
: A collection of web pages and resources found through the internet.
Networks
Network
: Two or more computers that are linked together and can communicate with each other.
Evalutation
Advantages
Users can share resources and peripherals.
Users can share the data held on disk drives, and it is easier to backup data held on a
central server
than on many individual machines.
Allows easy communication, VoIP, email, forums, and the connection of different types of computers.
Disadvanatges
User can become dependant on the network, and if the network stops operating they may not be able to access certain resources.
The efficiency of the network is often dependant on the network manager. Expensive to hire in some companies.
Difficult to make a network secure from outside threats such as hackers.
Performance of a network decreases as traffic degrades.
LAN and WAN
Local Area Network
: A LAN is a network of computers which are connected together in small geographical areas like schools or offices. These usually work at high speeds and they make use of connected peripherals such as printers.
Wide Area Network
: a computer network that joins computers together over large geographical areas. Many WANs are built for one particular company and are private. Others, built by Internet Service Providers, connect individuals to the Internet. Computers can be joined using the public telephone system, fibre optic cables, satellites or other means.
Network Interface Card (NIC)
: Allows data from the computer to be transferred over the internet. An expansion card that allows a computer to connect to a network.
Each NIC has its own unique 48 bit MAC address set by the manufacturer. This is considered to be a physical address because it can't change and is fixed to the hardware.
Protocols
Protocol
: A set of rules relating to the communication between devices.
Why are protocols important?
It allows different computers to communicate with each other in an organised manner. Different computers speak different languages. The computers would not be able to communicate with each other across the internet.
Can help computers identify themselves over the internet.
Ensuring correct addressing of source and destination and steering messages towards their target
Ensuring integrity and security of communication
Examples of protocols
TCP (Transmission Control Protocol)
:mailbox_with_mail:: Used with IP to ensure error free transmission and package switching.
HTTP (Hypertext Transfer Protocol)
:desktop_computer:: Used by web servers and browsers to transfer web pages.
IP (internet Protocol)
:package:: used to transfer all packages across the internet through routers.
STTP (Simple mail transfer protocol)
:email:: Used by mail servers and clients to transfer emails across the internet.
Layering Protocols/ Protocol Stacks
Why is it impprtanat? he protocol stack hides the complexity of the wireless interface and presents. ANy communication sent along a netwroms will pass through all the layers of the OSI model, and back again, in order t=for teh compyters to communicate.
Starn
Standard
: An agreed format that has been approved by a recognised standards organisation, such as the OSI seven layer model.
Domain Name System
Domain Name Server
: A server that has a list of domain names and translates these into Internet Protocol (IP) adressess.
IP address
: a unique address given to a computer using a network. It allows one computer to communicate with another one by sending data packets containing the destination IP address.
URL (Uniform Resource Locator):
This is the unique address of a website.
How a Domain Name System finds the IP of a URL:
The Domain name is resolved from left to right.
If the client has no cache record for that DNS it sends a query from that domain to its specified DNS server.
2.If the IP address is not found in the cache of the local DNS it refers to the root DNS server.
The root may know where the .uk server is.
It then refers to the .co DNS server.
The BBC server is found and the IP address is resolved.
It returns the IP address.
Network Topologies and Models
Peer to peer and client server
Client Server network
Features:
Ecah client (e.g a computer beloning to a student) is connected to the company central server where personal files and software programmes are securely stored.
Examples:
Schools and companies.
Cons:
If the server goes down, the rest of the netwrok will not be able to work proparly.
Peer to Peer Model
Features:
Here all the computers have the same status and there is no central server. A computer in this network can act as both a client and a server.
Pros:
Cheap. Files can be shared without any specialised hardware meaning that if one node goes down, only the files beloning to that node will be lost.
Uses:
Sharing files such as music online.
Cons:
Could promote piracy.
Other Topologies (the way that the network is arranged)
Physical Bus Topologies
Physical Star Topologies
Mesh Network Topologies
