Computer Networks Flashcards
Data packet
small piece of binary data from a file sent through a network
Two parts of data packets
Header
Payload
Header
contains .... the source IP Address Destination IP Address A checkSum The number of this packet within the sequence of packets
Payload
Data
Packet Switching (from computer A to D)
1.Computer A adds computer D’s IP
address to the packet
2.Computer A send the packet to the switch
3.Switch looks at address on packet
4.Switch compares address to stored list of addresses on the network
5.Switch forward packet to Computer D’s address
Benefits of packet switching
Packets would take the least busy route,making the network more efficient
More difficult for hackers to sniff packets and steal the data
If one router fails ,another one will be able to send the data.Packets will take different routes
Disadvantages of packet switching
Configuration of the router is complex
Routers will loss/Miss packets if they are working at full capacity
Data can be corrupted when being sent
Network Protocols
Define how you send data across the network and how it is converted
IP
Internet Protocol
defines. .
- structure of a valid data packet
- The structure of IP address
- How to reach an IP address
TCP
Transmission Control Protocol
defines. .
- How data is sent between two computers across a network
It relies on IP and guarantees delivery of packets or an error message is returned
HTTP
HyperText Transfer Protocol
defines. ..
- How hypertext is structured
- How hypertext is transferred between two computers
It uses TCP and IP
FTP
File Transfer Protcol
defines. .
- How (usually large) files or folders are transferred across a network
Uses TCP & IP. Web developers use this to transfer files to a web server
SMTP
Simple Mail transfer Protocol
defines. ..
- How a email is sent between email servers
Protocol Stack
Where protocols are stacked where protocols higher up the stack use protocols lower down
Advantages of Protocol Stacks
-Protocols higher up the stack hide how protocols lower work
-Allows different hardware to share data as they conform to the same protocol
-e.g an Ipad user can email a person with
Microsoft Word
Disadvantages of Protocol Stacks
- Technology improves but protocols may not implement the most efficient way to do something
- Agreeing and implementing a protocol is a time consuming protocol
Network
Two or more interconnected computers
Benefits of a Network
Communication between computers Sharing resources: -Hardware, Software, Data Data can be backed up Users can login to many computer Network security can be implemented from on location
Disadvantages of a Network (x4)
Viruses can quickly spread to other computers
Hackers can break into the network to steal data or damage computers
It can be expensive and complex to create a larger network
Diagnosing faults can be different in complex networks
LAN
Local Area Network
- within a small area/one building
example: Tesco express
WAN
Wide Area Network
- Across a wide area
- Made up of several connected LANs
example: Tesco
PAN
Personal Area Network
Types of Network Topologies
bus
star
ring
Advantages and Disadvantage of Bus
Advantages
- Less Expensive
- Less cables
- Quick to set up
Disadvantages
- If the main cable breaks , they all won’t work
- Data collisions are more likely
Advantages and Disadvantage of Star
Advantages
-If one computer goes down the rest are
unaffected
-Minimal network collisions
Disadvantages
- Expensive
- Extra hardware required
Advantages and Disadvantage of Ring
Advantages
- The data travels in one direction , which means the data transmission is quick
- Prevents network collisions
Disadvantages
- If the ring breaks they are all offline
- If the main cable breaks,the entire network goes down
Network Interface Card
Allows a laptop or standalone computer to be connected to a network
Network Cable
Used to connect the computer to the network
Its connect to the computer and a hub or a switch
Hub
A network connecting device which broadcasts data to all computers in the network
Switch
A network connecting device that sends data directly to the destination computer
connects more computers together than the Hub
Network Bridge
Connects two LANs or divides one LAN into two
Router
Connects WANs together
User access level
Controls what a user can do with computer resources
User Permissions
- None
- Execute
- Read
- Write
None
can’t open file
Execute
allowed to run a program
Read
Can open data files/folders to read the contents
Write
can open data/folders to edit the contents
Acceptable Use policy
What users can and cannot do on the network
Disaster Recovery policy
What do people have to do if a disaster policy to save data
Backup Policy
What data is backed up and how often
Archiving Policy
What happens to old data that isn’t needed anymore but may be useful in future?
