FIVE

Question 1

computer network

Answer 1

two or more interconnected computers for the purpose of communication

Question 2

advantages and disadvantges of computer network

Answer 2

ad:
share files
share hardware
easier and cheaper to communicate, e.g. email
update software on all computers at once
user accounts stored centrally so users can log in on any computer

dis:
susceptible to hacking, malware travels quickly
extra hardware is expensive to set up
dependent on servers—if the servers go down, there is big disruption

Question 3

wired vs wireless

Answer 3

wireless:
convenient, you can move around
cheaper
better for the environment
easy to add more users

wired:
wireless are less secure—any device can see the WAP so hackers can easily gain access
distance from WAP, obstructions or interference from other networks can weaken the signal strength
wireless have a lower bandwidth and are less reliable than wired networks

Question 4

star

Answer 4

fewer data collisions
easier to connect more devices
if device fails, no impact

expensive if wired network—each device needs own cable
if switch/server problem, whole network is affected
switch is expensive

Question 5

bus topology

Answer 5

aren’t affected by central switch
cheaper than star
if device fails, no impact

data collisions common—data needs to be resent so it slows network
more devices, more data collions so it is unsuitable for large networks
if cabe is damaged, whole network goes down

Question 6

network protocol

Answer 6

a set of rules that governs communication on a network

Question 7

ethernet

Answer 7

a family of related protocols used in data communication on a wired LAN

Question 8

WIFI

Answer 8

a family of related protocols used in data communication on a WIRELESS local area network
WLAN

Question 9

TCP

Answer 9

TCP—transmission control protocol
establishes a connection between the sending and receiving devices
then it splits the data into numbered packets that can be reassembled into the original data once they reach their destination
communicates with the receiving devices then it to make sure that all packets have been transferred correctly, if not, the missing/corrupted packets can be resent
sending devices then it gets confirmation when the transferis complete

Question 10

UDP

Answer 10

user datagram protocol
breaks down the data into packets without numbering them
they are read by the receiving devices then in the order that they arrive, even if they are in the wrong order
udp only sends each packet once and doesn’t check with the receiving devices then that everything has been received
saves time

Question 11

udp vs tcp[

Answer 11

tcp is more reliable
udp is fast and efficient

Question 12

IP

Answer 12

Internet protocol
operates on internet layer
establishes connections between routers and handles network traffic
IP addresses are added to the header of each packet at the internet layer
IP directs data packets to their destination across the internet using process called packet switching
each packet is sent btween a series of routers—each router reads the packet’s header and uses the IP address to decide which router to send the packet to next

many possible routes, changes depending on network traffic
very efficient

Question 13

HTTP and HTTPS

Answer 13

hypertext transfer protocol
used for accessing and receiving web pages via the internet
protocol requests a web page from the server
server then sends its response which contains the web page

HTTPS (secure HTTP)
encrypts the informationso it cannot be understood by an eavesdropper

Question 14

FTP

Answer 14

file transfer protocol
used for sending or retrieving files to or from a FTP server

Question 15

SMTP

Answer 15

simple mail transfer protocol
email is sent from a computer then it is sent to a mail server using smtp
mail server then relays the message through mail relays
then the email arrives at destination server

Question 16

IMAP and POP

Answer 16

POP - post office protocol
downloads every new message to local device so that message is no longer available on the server

IMAP - instant message access protocol
leaves messages on a server
can be accessed by multiple devices
only removed if someone deletes them

Question 17

layer

Answer 17

a group of protocols with similar functions
self contained

Question 18

application layer

Answer 18

where the network applications, e.g. web browsers or email progrmas, operate
HTTP, HTTPS, IMAP, FTP, SMTP

Question 19

transport layer

Answer 19

setting up communications between two hosts and they agree settings such as size of packets
TCP, UDP

Question 20

internet layer

Answer 20

Adding IP addresses to data packets. Addresses and packages data for transmission. Routes the packets across the network
IP

Question 21

link lauer

Answer 21

where the network hardware such as the NIC and OS device drvers are located
WIFI and Ethernet

Question 22

advantages of layers

Answer 22

breaksthe network communication into manageable pieces
helps developers to concentrate on only one area of the network

as layers are self contained, they can be changed without the other layers being affected

having set rules for each layer forces companies to make compatible, universal hardware and software, so different brands will work with each other

Question 23

need for network security

Answer 23

networks can be vulnerable to attacks by criminals
sensitive data stored on networks

authentication
encryption
mac address filterningi
firewalls

Question 24

Authentication

Answer 24

using credentials to check if a user is who they say they are
credentials are then verified to see if they match what is stored b y the system

Question 25

encryption

Answer 25

converting plaintext into cipher text so intercepted data cannot be understood public key—asymmetric encryption 2 keys used: public (for encryption) and private (to decrypt) so it is more secure as you never have your send/ reveal decryption key private key—symmetric encryption single key used to encrypt and decrypt—must be given to the recipient to decrypt and encrypt

Question 26

MAC address filtering

Answer 26

wireless router can block specific MAC addresses black list and white list

Question 27

firewalls

Answer 27

barrier between a network and the internet sparates trusted network from untrusted network prevents unwanted traffic from entering a network by filtering requests to ensure they are ligitimate data sent around network in small packets are checked to see where they are comming from and going to packets that don’t match filtering rules are dropped constantly monitors incoming and outgoing network traffic decides whether to allow or block the traffic based on the security rules that have been set can bloock certain malicious computers by filtering packets from a certain IP address can prevent access to certain ports on the network