Networks part 2 Flashcards
Largest WAN
The internet
WHAT IS THE INTERNET
The internet is a collection of interconnected networks spanning the world
The concept of the Internet as a network of computer networks
Difference between internet and world wide web
The internet is NOT the same as the “World Wide Web” which is just a service on the internet
The internet itself is just the hardware, the cables, the wireless connections and the routers that make the internet what it is
A Domain Name service role in the conversion of a URL to an IP address
- URL request by browser made from user e.g. www. bbc.co.uk
- The browser sends the domain name to a domain name server
- The DNS maps the domain name to an IP address and returns it to the browser
- GET request for the webpage / resource is sent to the web server using the IP address
- Requested webpage/resource is returned to the clients web browser
Why are web addresses used instead of IP addresses
When you request a page on a server, you would need to refer to its IP address.
This is not very convenient for humans as we are not very good at remembering sequences of numbers – we prefer to use words
Web addresses which are easier for humans to remember are converted to IP addresses for routers by a Domain Name Service (DNS) revolver server
What is domain name service made up of
A Domain Name Service (DNS) is made up of multiple Domain
Name Server
What do servers do
Servers provide services
(e.g. Web server -> Web pages, File server -> file storage/retrieval)
E.g.
Clients request/use services from a server
Purpose of the cloud
Severs can be used to store data and programs remotely that can be accessed and used over The Internet
This is known as ‘The Cloud’ or ‘Working in the Cloud’
Advantages of The Cloud (storage) (rather than storing data and programs on your PC):
Access information any time
Access information anywhere
Access information from any device
A large storage capacity
Automatic backup of data
Easy online collaboration
No need to buy expensive hardware or store data or run complex applications
No need to pay IT staff to manage the hardware
They provide access to anything, anywhere, automatic backup and collaboration of document
Disadvantages to the cloud
Need connection to the Internet to access files or applications
Dependent on host for security and back ups
The hosting company could be targeted by online hackers - data stored in the cloud can be vulnerable to hackers
Subscription fees for using cloud storage and software may be expensive
Download and upload speeds can be affected by the internet connection
What is hosting
Hosting is when a business uses its servers to store files of another organisation
_____________________________
Websites are stored on servers dedicated for this purpose
This is known as hosting
Hosted solutions provide 24/7 access, multiple users and greater security
Types of network topologies
Star network topology
Full/partial mesh network topology
What is a network topology
A given arrangement of all the elements you need for networking.
What is a star network topology
Type of network topology where:
Includes a central switch
All devices connect into the central switch
The switch is intelligent and makes sure traffic only goes where it is intended
Advantages of star network topologies
If a single cable breaks only that computer (connected to the switch) is affected. (if one link fails, all the other devices will continue to operate)
There will be less network traffic and fewer collisions
Adding or removing devices is easy and can be done without affecting the entire network
Data can be directed to the intended node directly without having to pass along the complete network
Disadvantages of star network topology
Network operation depends on the functioning of the central component (file server or switch0 - if this fails, then so will the entire network
It requires a lot of cables as each computer is connected individually to the central component and so will be expensive
What is the mesh topology
Each of the network nodes, servers, client computers and printers are interconnected with one another
Every node not oly sends its own signals but also relays data from other nodes
Every node is connected to ever othe rnode
Advantages of mesh topology
Data can be transmitted from different devices simultaneously
Even if one of the components fails there is always an alternative route for the data
It can handle high volumes of data traffic
Adding more devices will not hamper the transmission of the data as all nodes help to transmit the data
Disadvantages of network topology
The overall cost is expensive compared with other topologies since there is a lot more cabling and switch hardware required
Very difficult to manage as it requires continuous supervision
Disadvantage is that there is a lot more cabling and switch hardware are required which will add to the cost (be expensive and impractical) for large networks
Example of a wired connection
Ethernet
Advantages of Wired networkds
Very high bandwidth up to 100 Gbps
Security is good. A user has to physically plug their computer into the network using a cable
There should be no interference with the signal on a network cable
Disadvantages of of wired network
Setting up is more difficult. Cables have to be run all over the site
Not very mobile. A user has to plug the computer into a wall socket and cannot use it in a room without one. Contact ids lost as soon as it is unplugged if the user wants to move to another room
Advantages of wireless networks
Installation is easy. All that is needed are wireless access points and NICs for any computers such as desktop computers, that do not have them build in
Cost. Cheap. Just cost of wireless access point
Very mobile. Users can access the network from anywhere on the site. Can move from room to room and remain connected
Disadvantages of wireless networks
Far lower bandwidth. The latest version of Wi-Fi can offer speeds from 433Mbps to 2 or 3 Gbps. Compared to speeds of up to 100 Gbps for wireless networks
Security is poor. Anyone within range can see the network and connect to it to use it. The access point must be secured with a security password. Some form of encryption must be set up
Interference: The signal can be affected by walls and electronic equipment such as microwave ovens. It is also affected by distance from the access point and the number of connected devices.
