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1.3 Networking - Coggle Diagram
1.3 Networking
MAC address
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If the IP address is not found it is passed up to the next level of Domain Name servers. If the IP address cannot at the top level (.com or co.uk etc) an error is returned to browser.
4 layer model
Application layer
This encodes the data that is being sent so that it will be understandably by the recipient. This might involve formatting data and adding a header according to the protocol such HTTP or FTP.
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Network layer
This attaches the IP address of the sender so that computer that receives it knows where it has come from.
Link layer
This attaches the MAC addresses of the sender and the recipient allowing for the packet to be sent to a specific device on a LAN
DNS and URLs
1) Websites are stored on webpages that are connected to the internet. Each website has it's own IP address. As we have seen IP address are difficult to remember so web sites are given a domain name or a Uniform Resource Locator (URL)
2) When you type in a URL to the address bar this is sent as a request to the a domain name server. This is part of the Domain Name System and it controls how webpages are retrieved.
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8) If the IP address is not found it is passed up to the next level of Domain Name servers. If the IP address cannot at the top level (.com or co.uk etc) an error is returned to browser.
Protocol
Email Protocols
POP- Post Office Protocol. POP receives and holds emails until they are picked up by a user. When the user checks there email, it is downloaded from the server and then server deletes it so no one else can see it.
IMAP- Internet Messaging Access Protocol. Its more useful for people with multiple devices as it keeps the copy on the server until the person deletes it.
SMTP- Simple Mail Transfer Protocol. This protocol allows for emails to be sent between email servers. This is particularly relevant when the server and recipient have different email providers .
Web Protocols
HTTP- Hypertext transfer protocol. Requests that the web server transmits the requested web page to the viewer's web browser.
HTTPS- Hypertext transfer protocol secure. Its a secure website unlike http, You would want HTTPS if its like a bank website or a website asking for personal informational.
Other Protocols
TCP- Transmission Control Protocol. TCP is responsible for how messages are broken into packets and reassembled at the destination. TCP is also responsible for checking for errors and if necessary resends lost packets.
The IP/ Internet Protocol. protocol allows for a device to be identified on the internet and allows for appropriate packet routing.
Connection Media
Ethernet
Ethernet cables are the most common method of connecting devices on a network. They are sometimes referred to as unshielded twisted pair cables (UTP)
Co- axial
This connection method is again based on the use of a copper wire. Co-axial cabling is often used for cable TV and broadband. It has a higher bandwidth than Ethernet cable and can allow for greater distances to be travelled before being boosted. It also has significantly more robust construction. This stronger construction leads to less interference or distortion of the data.
Fibre Optic
A Fibre Optic cable uses light to send stuff across the world These cables are found under the sea and are alot faster than copper cables
Network Hardware
Router
A router is responsible for forwarding data packets between different computer networks. The packets are forwarded using many different protocols. The devices in your home most likely have a static IP address, this is useful as it helps be making other routers be found.
Hub
A hub acts as a point that can connect all devices on a network together, in much the same way as a bike wheel has a hub to hold all the spokes in place. A hub receives data from computers connected to it. Data on a Local Area Network is carried by a data type known as a frame (once ready for transmission on the internet this is transferred to packets).
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Wireless Networking
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Wireless security should be considered are there a number of measures that are used on wireless networks to prevent data loss. These include:
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Disabling the broadcast of the Service Set identifier (SSID). This hides the network from other potential users.
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Topologies
Star
One path to server, easy to tell which path broke, cheap. no self healin
Mesh
All the devices are connected together, if one path brakes it takes another (Self Healing). Hard to tell which path has broke.
What is the internet
The internet started in the 1960s as a way for US government researchers to share information. In the 60s computers were large and immovable and the storage that was used was little better with huge magnetic tapes being used to store data.
IP addressing
Every computer in the world has a unique IP address. The user can change the IP; mobile devices tend to have dynamic IP addressing meaning that it can change.
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The current system is known as IPv4. It takes an address that is made up of 4 values up to 255 (8 bits).
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