Networking-Textbook Flashcards
define bit rate
this is a measure of transmission speed of data over a telecommunication line.
- it measures how many bits can be transmitted in 1 second.
- dial-up = 54k bps
- fast= 1000 million bps
Describe WLAN
wireless local area network
-uses the wifi (wireless fidelity) standards
describe asynchronous
- clocks are not synchronized at the beginning of transmission.
- known as best effort transmission.
list in order of bandwidth
- modem/dial up
- ethernet
- wireless
- wireless-G
- fast ethernet
- wireless-N
- gigabit Ethernet.
Data security features
A NOS protects the data and hardware from unauthorized users.
advantage of proxy server
- hide one’s IP address
- increase efficiency- temporarily store images and text from different websites. acting as a cache of webpage.
- view blocked websites
- increase security.
define protocols
is an agreement or standard on how data is to be exchanged over a network.
describe bus topology
- the individual computers are connected to a central cable called central bus.
- the server is also connected to the bus.
- it is easy to add extra clients to the bus by tapping the cable and a new connection is added.
- Disadvantage: the system is slow.
- only 2 computers can exchange information with each other at any particular time.
- if 2 computers want to exchange data, then the other computers must wait until their transaction is finished.
NB: the clients share a central cable, only 1 client can transmit data at a time.
compare grid computing to the use of supercomputers
- grid is much more cost-effective.
- supercomputers are manufactured in fewer quantities thus expensive.
- can be done on conventional computer hardware and connecting them via a network
list the 3 networking layers
- application layers
- internet layers
- hardware layer
Define TV cable
the same cable that supplies TV can be used to connect to the Internet.
Define Modem
this is the hardware that handles the communication to the outside world.
- the modem is connected to the telephone line or cable YV line on one side and to the router on the other.
Describe ISDN
integrated services digital networks:
-faster than analogue dial-up.
define proxy server
is a computer that acts as an intermediary between the user’s computer and internet.
Define client
this is a computer program or computer that requests a service from a server.
describe how grid computing and distributed processing work
[Network distributed parallel processing
- a special software program distributes the computation task over the network to the different computers.
- the computers then work on their assigned task in parallel and send back the result to the central server.
NB: this is known as [network distributed parallel processing.]
list disadvantage of P2P networks
- difficult admin
- security
define timesharing
this is the sharing of the processing power of the mainframe.
define firewall
is a computer with software that protects a LAN from the WAN. allowing certain data packet to pass through.
PDA stands for ?
personal device assistant
list ways to monitor user behavior on a network
- key loggers
- system performance monitors
- surveillance software.
Intellectual property issue:
- networks make it easy to share and distribute copyrighted material, both legally and illegally.
- the copyright owner either benefit from the possibilities or may be harmed.
describe synchronous
- both senders and receivers possess an internal clock.
- clock run at same speed.
define supercomputer
these are optimized for high computation speed.
describe HTTP
hypertext transfer protocol
-specifies how a webpage should be transferred over a network so that it can be viewed by a browser.
what does UPS stand for
uninterruptible power supply
Define server
this is a central computer that is able to provide various services to the connected clients.
Describe redundant topology
- 1 computer is connected to 1 or more computers.
- if one computer is down due to maintenance, then the data will travel a different way to avoid the problem.
- the internet can be considered to possess a redundant topology.
- generally not used in LAN
- requires alot of cables and 1 computer would then have to be connected to several other computers.
NB: there is no single central server. if one of the host breaks down, then the data is still able to travel a different route to the destination
Define WAN
networks that stretch over a large geographical area.
- satellites and fibre optic cables are commonly employed here to connect different continents with each other.
- example is internet
describe switch
more intelligent than hubs:
-able to learn for which computer the data is intended
advantage:
-reduces network traffic and increases network speed.
define packet sniffer
is a program that monitors the data packets that pass over a network.
Describe hub
is the least intelligent.
- has 1 input port and several output ports.
- data that arrives at the input port is simply copied and distributed to all of its output ports.
disadvantage:
- generates unnecessary network traffic.
- cause network to slow down.
Describe routers
most complex devices:
-interpret the IP address of the computer and make sure that the data is forwarded to the correct port.
Advantage of networks:
Easier system maintenance
an admin is able to perform centralized system maintenance and can install updates over the network without having to access each client computer individually.
what can a network policy include?
- archiving
- disaster recovery
- network usage
- redundancy specifications
- failover
define network topology
This is the arrangement of the computers on the network.
list things that causes network failure
- Network overload
- viruses and worms
- hard disk failure
what does SAN stand for?
storage area network
describe FTP
file transfer protocol
-used by programs designed for uploading and downloading files from a file server.
data integrity;
- data stored on databases can be modified by several people. These people can access the database over a network
- how can this data be protected from accidental or deliberate modification?
- modified medical data, eg, can have serious negative consequences for the patients.
Which was the first network that covered a wider geographical area?
APRANET
1983
List the general moral imperatives
- contribute to society and human wellbeing
- avoid harm to others
- be honest and trustworthy
- be fair and take action not to discriminate.
- honour property rights, including copyrights and patent.
- give proper credit for intellectual property
- respect the privacy of others
- honour confidentiality
describe wireless
the advantage:
- it is independent from a cable.
Access and authentication
- which user has what rights?
- what are the various users allowed and not allowed to do?
- if unauthorized users have access to the resources of the network, then there is the danger that the data stored on the servers of the network can be either modified or passed on to other people.
define collision
when more than one computer send data at the time
- the computers had to resend their data.
list the features of NOS:
- user management
- permission management
- allows data access
- allows hardware access
- data security features
- backup features
- remote access
data is sent over the network in ?
packets.
describe star topology
- clients are connected to a central server.
- if 2 clients want to exchange data, then the data must be passed through the central server.
- if the central server fails, no clients are able to communicate with each other.
- if a new computer needs to be connected to the server, then a separate cable connection is required.
NB : the clients can communicate with each other only through the central server.
describe POP3
post office protocol 3
-used when receiving emails.
Disadvantage of networks
Intellectual property
This relates to issues of software licensing.
the organization must have the licences to install the software on a network.
Describe a web host
this is a computer that stores the websites of different companies.
Define Peer to Peer [P2P]
this is a highly decentralized network.
-each host connected to the network serves both as a client and as a server, hence different computers can exchange data directly with each other.