4.9 Fundamentals of communication and networking Flashcards
Define serial transmission
Single bits are sent one after another along a single wire
What is thick vs thin computing?
The thickness of a client computer refers to the level of processing and storage that it does compared to the server it is connected to.
What is bit rate?
The number of bits sent per second
What is baud rate?
The baud rate is the rate at which the signal changes
What is bandwidth?
The range of frequencies that a transmission medium can carry. The larger the range, the more data can be sent. expressed as bits per second bps.
What is asynchronous transmission?
Using asynchronous transmission, one byte at a time is sent, with each character being preceded by a start bit and followed by a stop bit. The start bit alerts the receiving device and synchronises the clock inside the receiver. A parity bit is also usually included.
For one character, a total of 10 bits is needed, start bit + parity bit + data + stop bit.
What is an IP address?
Internet protocol.
IP addresses indicate where a packet of data has come from or is going. Routers use this data to direct the packet.
If a domain name is associated with a specific IP address, the IP address is the address of the server that the website resides on
What is a protocol?
a shared set of rules to govern communication between devices.
What features make up a url?
eg. http://www.website.com/folder/webpage.html#element
http = Method www = host folder/webpage = location #element = resource
What does URL stand for and what does it do?
Uniform resource locator, it specifies the location of a resource on the internet, so a browser can request it from the website server.
What are advantages/disadvantages of thin computing?
Advantages:
- Easy to set up/maintain/add terminals.
- Software and updates can be installed on the server automatically and distributed to each computer
- More secure as data is kept in one place
Disadvantages:
- Reliant on the server, so if it goes down, computers lose functionality
- Server demand increased
- Requires a powerful server which is expensive
- Maintaining network connections for portable devices uses more power than local processing
What are advantages/disadvantages of thick computing?
Advantages:
- They are robust and reliable, providing greater up-time
- They can operate without continuous connection to a server
- They are better for running more powerful applications
Disadvantages:
- More expensive/ higher spec computer needed
- Installation of software required on each computer seperately
- Integrety issues with distributed data
What are advantages/disadvantages of client-server networks?
Advantages:
There is better security
Centralised administration
Data/resources stored on server - can be shared easily
Disadvantages:
Its expensive to set up
Professional IT staff are needed
Heavily reliant on the server, if the server breaks then the whole network stops working
What are advantages/disadvantages of a peer-to-peer network?
Advantages: Cheap Users can share resources Its not hard to maintain No dependence on a server
Disadvantages:
Can be slow when many users want to use the network
Each computer has equal status - harder to manage security/administration
Define parallel transmission
Bits are sent down several wires simultaneously
What are advantages of serial over parallel transmission?
Serial doesn’t suffer from skew and crosstalk
Serial is cheaper
Parallel data transmission has a limited data rate and distance at which it can reliably operate
What are advantages of parallel over serial?
Parallel transfers data quicker and the interface is simpler
What is skew and crosstalk
Skew:
Where bits travel at slightly different speeds down each wire in a parallel bus
Crosstalk:
Induced signals in adjacent wires of a parallel bus caused when a signal on one or more wires varies rapidly
Define synchronous data transmission
Streams of bits are transferred at a constant rate.
The transmitter and the receiver are synchronised using a common clock signal
Define asynchronous data transmission
Start and stop bits are used to control the communication
Data is transmitted when it is available rather than at specific intervals.
This means there can be periods of time when the transmission channel is idle
Compare synchronous with asynchronous data transmission
Synchronous is faster because fewer bits have to be transmitted (no control bits)
Asynchronous is cheaper and particularly suited for low speed connections (keyboard and mouse)
Describe the purpose of start and stop bits in asynchronous data transmission
Start bit signals the arrival of data at the receiver. This enables the receiver to sample the data correctly by generating clock pulses
Describe peer to peer networking
There is no central server, all the computers have equivalent capabilities and access right
Peers can communicate directly with each other
Suitable for LANs
Describe client-server networking
Involves a central, powerful computer called a server, and a number of client computers that need to connect to the server to carry out specific tasks
Define a Fully qualified domain name (FQDN)
FQDN is a domain that specifies an exact resource and can be interpreted in only one way
Will always include the servers host name
FQDN example: https://www.bbc.co.uk/new/index.html
Not a FQDN: https://bbc.co.uk/new/index.html
Define a domain name
Identifies an organisation or individual on the internet
Uses alphanumeric characters to make it easy to remember
What is the purpose and function of the domain service and its reliance on the DNS system?
Domain Name system (DNS) was invented so that users could use a memorable name called a domain name to refer to a network
Compare physical and logical topology
Physical topology is the physical layout of the wires that connect computers on a network
Logical topology is how the packets of data flow around a network
