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.
what does TLS stand for?
transport layer security
who create the SETI@home
by Space sciences laboratory of university of California
- search for extraterrestrial intelligence
-
define dumb terminals
these are terminals that do not perform any computing themselves but rather they are composed of a keyboard and a monitor connected over a cable to the mainframe.
- each terminal receives a certain amount of computation time.
- cannot communicate with other terminals unless going through the mainframe.
Describe analogue dial-up
connection established over regular telephone line to the ISP.
disadvantage:
- slow
- cannot use internet and phone at same time.
Define host
this can be a client or a server,
but is generally used to describe servers that provide certain services to the network.
Disadvantage of networks:
Control
there is a possible loss of control over data.
users may compromise the integrity of the data by modifying files if the access allowed by the user has not been configured properly.
Disadvantage of networks:
Security
a range of security threats [unauthorized access, worms or viruses] must be handled appropriately.
define BNC adaptors
these are cables belonging to an older ethernet standard.
-Bayonet Neill concelman
Define router
is a piece of hardware that is needed if more than 1 computer should have access to the internet.
Allows hardware access
A NOS allows users to access hardware, such as printers and scanners, which are connected to the network.
what does RAID stand for ?
redundant array of inexpensive disks
define extranet
these are extensions of an intranet.
who created folding@home
by stanford university
- since 2009, 400000 computers
- 4.51 million participated.
- project focused on biochemistry
Define WLAN
- Wireless local area network
- are connected using radio transmission and not with cables.
- the clients connect to the network over so called hotspots or accept point.
define data centres
is a facility that contains a collection of several powerful computers.
Advantage of networks:
Easy sharing of data
A central server provides the data to the clients and different users can login to the server to retrieve the required data.
describe the use of screen savers
- Volunteers can install a screen saver on their computer which then becomes active when the user does not use the computer.
- the screen saver loads calculations from a server and sends back the results.
- this way, users can lend some of their CPU power to scientific projects.
Define central router
a device which controls the flow of data and prevents collision
Computer networks are composed of?
2 or more computers connected together.
-networks allow for data exchange.
describe glass fibre
or fibre optic
- the signals are transmitted using light over glass fibre optic cables.
- very fast.
- very expensive
How does computers communicate?
by using TCP/IP [transmission control protocol/ internet protocol] to communicate with each other
list network security problems
- hacking
- Denial of service attack (DOS)
- Network sniffing
- Phreaking
- phishing
- cracking
- malware
User management
system admin can assign different permissions to the different users of the network.
-special utility programs help in maintaining an overview of the users and their associated rights.
Describe ring topology
- there is no single central server since the computers are connected in a ring shape.
- data is passed on in one direction only.
- 1 computer is configured as a server but several servers may exist within the ring, each one configured to perform a different function.
NB: the data is passed in a circle until it reaches the destination computer.
what does SSL stand for?
secure socket layer, encryption methods that are commonly used to encrypt websites.
What is a network operating system? NOS
this is an operating system that is specifically designed to operate and manage computer networks.
data security:
- how can data stored on a network be protected from accidental loss?
- system admins need to make backups of the data.
list advantage of client-server
- centralized
- control
disadvantage of Grid computing
- the network connection can become a bottleneck and substantially slow down the whole task
- not suitable for all types of calculations and a careful cost-benefit analysis must be done before selecting a particular hardware solution.
- requires volunteers willing to participate in the project.
Define Network cables
-ethernet cables in which a computer can use to connect to the router to access the internet.
Define Intranet
is a network that belongs to one particular organization.
Mainframes and supercomputers both follow ?
the philosophy of centralization
Define internet
this is a worldwide network of interconnected computers.
define grid computing and distributed processing
these are examples of extremely decentralized computing.
- the computer network itself essentially becomes the supercomputer.
Define LAN
these are networks that extend over a limited geographical area
- fast data transfer rate
- administrated by a person who has full control over the network.
Describe bluetooth
this is also a wireless standard. bluetooth works over short distances.
describe HTTPS
secure hypertext transfer protocol
-uses encryption to make data transmission more secure.
Allows data access
A NOS allows users to access data stored on a server.
Advantage of networks:
Centralized management of software
system administrators have to install software only once onto the central server.
the clients can then use the software right away.
NCSA Mosaic web browser released in?
1993
what can reduce the reliability of the computer hardware and increase the risk of fire?
dust and dirt.
list the 2 notable examples in which grid computing is in active use.
- The project SETI@home [University of California]
- The project folding@home [conducted by stanford university]
ISP offers different methods of connecting to the Internet, as it also depends on?
the geographic location and the general infrastructure of the area.
Define Cloud computing
is a general term that describe a collection of services that are provided over the internet by a company to its customers.
define ethernet
this is one of several ways to connect a computer to a network.
- it relies on copper wires for transmitting the data.
- originally, computers were connected to a central copper cable.
define audit trail
a log file which stores the activities of the users.
Back up features
A NOS comes with utility programs that assist in making periodic backups of the data stored on the server.
list software licensing model
- single-user
- multi-user
- concurrent licence
- network licence
- site licence
Describe Wimax
Worldwide interoperability for microwave access.
-phone networks [digicel]
list advantages of P2P networks
- simplicity
- no central system admin is needed
- data sharing
privacy issues
- it is possible to monitor the actions of users over a network
- this monitoring can infringe on a person’s right to privacy
list things that make networks more secure
- login/password
- biometrics
- physical access control
- encryption
- installation of firewalls
List different types of servers
- Mail server - stores emails until they are retrieved by the user.
- Web server- stores websites to be viewed by the public
- File server- Stores files to be accessed by authorized users of a LAN
- Video server- Stores videos files to be viewed by the clients of the LAN. Video servers are sometimes used to make videos available to skls and universities.
Client-server architecture is strongly?
centralized
- a number of different clients are connected to a powerful central server.
- if 2 clients want to exchange data with each other, then they must go through the central server.
- can be configured to handle printing, file storage, emails.
NB: if the central server breaks down, then the clients are isolated and without a connection
define ADSL
asynchronous digital subscriber line
- a regular telephone is used to transmit a digital signal.
advantage:
- possible to use internet and telephone at the same time.
- fast transmission speed.
disadvantage:
- speed depends on distance to the next telephone station
- ADSL not available everywhere.
Remote access:
this features allows users to operate a computer over the network just as if they were sitting in front of the remote computer.
-remote access can also refer to the simple accessing of data stored on a server, such as the uploading and downloading of files.
what does TCP and IP stand for ?
transmission control protocol
internet protocol
define baud rate
represents the number of electrical impulses that are sent over a line.
define bandwidth
is a measure of the frequency spectrum that is used to transmit data over a network.
ethernet=broadband
dialup= narrowband.
the computer is located in a large room in which they can be ?
maintained and managed
Network card.
a device in which a computer can use to have network functionality
What does VLAN stand for
virtual local area network.
Define VLAN
this is a software solution that divides up a computer network into several subnetworks, without requiring extensive rewiring.
Define WWW
this is one of the area of application in which hypertext documents can be sent over the internet.
Define mainframe computers
these are primarily designed to store and process large quantities of data
- designed to be highly reliable
- possible to exchange computer parts without having to shut down the system.
the proxy server is unable to hide blocked servers from ISPs
FALSE
_____ is a network security problem that refers to illegal and criminal activities. it can also refer to the copy protection of a piece of software.
cracking
networks can fail due to _______as they can be programmed to spread so quickly that the network become congested.
malware
________ _________ programs can be used to spy on login or password combinations
keystroke monitoring
________ is a measure of the frequency spectrum that is used to transmit data over a network. it determines how much data can be transferred per unit time
bandwidth
a _____ _____ is a computer that acts as an intermediary between the users’ computer and the internet. all internet traffic is routed through it before it reaches the user’s computer.
proxy server
a ___ ____ is also known as a “server farm”
data centre.
This method of security only allows certain users access to certain computer.
physical access control
___ ____ is used for employee monitoring purposes and for surveillance. it keeps a detailed log of the activities of a user
audit trail
ISPs have performance monitoring software to determine whether customers are using the internet in an unacceptable manner
true
SSL and TLS are _____ methods used to secure websites
encryption
a network can fail due to ___ ___, which is too many people trying to access a server at the same time.
network overload.
the data on a network is sent as a continuous stream
false
