S6 - Networks (Done) Flashcards

Question

What are the advantages of star topologies ?

Answer 1

If one device/cable fails the rest of it is unaffected, simple to add more devices as each is connected to the switch with its own cable, tend to have better performance than other set ups - devices connected to switch directly so they can transmit at the same time, and has very few data collisions.

Answer 2

Hardware - such as wires for each device connected and the switch - can be expensive, if there's an issue with the switch or server it can affect whole network, maximum possible connections on the network is determined by the switch - if you need more connections you'd need to buy a new switch.

Answer 3

Use a backbone cable - a bus - to connect all devices with a terminator at each end to stop data reflecting back along the bus which would cause interference.

Answer 4

Network is unaffected if one device fails, aren't dependant on central switch to keep network running, and are relatively cheap as length of wiring needed is less and hardware needed (bus and terminators) is less to buy and maintain.

Answer 5

Data collisions are common - so data has to be resent slowing network, the more devices the more likely a data collision - unsuitable for large networks, to avoid collisions devices must wait for bus to be free slowing the network, and if bus is broken it splits network into separate parts - without terminators at both ends causing reflected signals which can shut down the network.

Answer 6

A set of rules for how devices communicate and how data is transmitted across a network.

Answer 7

How communication between two devices should start and end, how the data should be organised and what the devices should do if data goes missing.

Answer 8

Data is split into equal sized packets - each containing extra information like destination and source addresses and a checksum - used to find errors.

Answer 9

A group of protocols which have similar functions.

Answer 10

They're self contained - not dependent on knowing what happens in other layers to do their job, and each layer serves the one above it - doing work to accommodate for an action on the layer above.

Answer 11

Layer 4 - application layer, layer 3 - transport layer, layer 2 - internet layer and layer 1 - link layer.

Answer 12

Provides network services to applications - involves protocols such as HTTP, FTP and SMTP, and is responsible for things like file, email and data transfer.

Answer 13

Sets up communications between two devices, splits data into packets and checks packets are correctly sent and delivered - including TCP and UDP protocols.

Answer 14

Responsible for adding IP addresses to data packets, directing them between devices and handling traffic, used by routers - includes the IP protocol.

Answer 15

Passes data over the physical network, responsible for how data is sent as electrical signals over cables, wireless and other hardware, and for interpreting signals using device drivers - includes protocols such as Ethernet or wi-fi.

Answer 16

Breaks network communication down into manageable pieces developers can concentrate on without worry about other areas, they are self contained so can be changed without affecting other layers, and the set rules for each layers forces companies to make compatible, universal hardware and software.

Answer 17

Hyper Text Transfer Protocol - used by web browsers to access websites and communicate within we servers.

Answer 18

HTTPS is like HTTP but secure (Hyper Text Transfer Protocol Secure) - performs the same function but encrypts all information sent and received.

Answer 19

File Transfer Protocol - used to access, edit and move files between devices on a network.

Answer 20

Internet Message Access Protocol - used to retrieve emails from a server.

Answer 21

Simple Mail Transfer Protocol - Used to send emails, and to transfer emails between servers.

Answer 22

Used in the transport layer, they control the packaging and unpackaging of data.

Answer 23

Transmission Control Protocol - establishes connection between sending/receiving devices, splitting data into numbered packets to be reassembled into original data at the destination, even if they arrive out of order.

Answer 24

User Datagram Protocol - breaks data into unnumbered packets , so are read by receiving device in order they arrive.

Answer 25

Communicates with receiving device to make sure all packets transferred correctly, and if not the missing/corrupted packets can be resent. Sending device receives confirmation when transfer is complete.

Answer 26

It doesn't - only send each packet once and doesn't check with receiving device that everything has been received, saving time, however no way of knowing if packets have gone missing in transit.

Answer 27

For applications that need fast, efficient transmission (like live video streaming - small hiccup in video quality is better than a delay).

Answer 28

For when you need a reliable connection (downloading files - missing packets could cause file to be corrupted or unusable but you would have to redownload it)

Answer 29

Internet Protocol - operating on internet layer establishing connections between routers and handling network traffic.

Answer 30

Unique numbers assigned to every device connected to an IP network - added tot he header of each packet at the internet layer.

Answer 31

Directing data packets tot heir destination across the Internet and other IP networks using packet switching.

Answer 32

Where each packet is sent between a series of routers - each router reading the packets IP address to decide which router to send it to next, which way the data is sent changes depending on network traffic so some packets take different routes.

Answer 33

A family of protocols commonly used in WLANs, operating on the link layer - where units of data are called frames instead of packets.

Answer 34

Over two frequency bands, 2.4 GHz - greater range and better at getting through walls and other obstructions, and 5 GHz - which is faster over short distances.

Answer 35

The bands are split into numbered channels that each cover a small frequency range - channels in the 2.4 GHz band overlap so networks using adjacent or overlapping channels can cause interference.

Answer 36

Another family of protocols that operates on the link layer, similar to Wi-Fi is handles data transmission between devices on LANs but is specifically for wired connections.

Answer 37

The process of trying to protect networks, data, programs and computers against damage, cyber attacks and unauthorised access - covering technologies, practices and processes used to do this.

Answer 38

Cyber attacks against governments or militaries.

Answer 39

/pentesting - when organisations employ specialists to simulate potential attacks to their system - to identify possible weaknesses in cyber security, which are then reported back so these vulnerabilities can be fixed. There can be white box or black box penetration testing.

Answer 40

It simulates a malicious insider who has knowledge of the current system (an employee), person carrying out the test is given user credentials to see what they can do with them.

Answer 41

Simulates an external cyber attack, person carrying out the test not given any credentials but is attempting to hack the organisation in any way they can.

Answer 42

/malicious software - code designed to cause harm or gain unauthorised access to a computer system - often installed onto someones device without their knowledge/consent.

Answer 43

Where a hacker encrypts all the files on a computer - the user receiving a message demanding a large sum of money paid in exchange for a decryption key.

Answer 44

Displays unwanted pop-up ads that can't be closed.

Answer 45

It monitors the user by tracking actions like key presses and sends this info to the hacker who could then work out things like passwords and bank details.

Answer 46

They alter permissions, giving hackers administration level access to devices.

Answer 47

They attach to certain files, users spread them by copying infected files and activate them by opening the infected files.

Answer 48

They work like viruses but they self replicate, allowing them to spread very quickly, exploiting weaknesses in network security and slowing down network traffic.

Answer 49

They are disguised as legitimate software, tricking users into installing them - they don't replicate themselves.

Answer 50

A way of gaining sensitive information or illegal access to networks by influencing people - can be done through pharming, phishing, shouldering and blagging.

Answer 51

User is directed to a fake version of a website that looks like the real thing, when the user puts in personal information, the criminals can then access their genuine account. Often carried out using malware to redirect users from the genuine site to the fake one. Up to date anti malware software can reduce the risk of these, and internet browsers can use web filters to block access.

Answer 52

When criminals send out emails/texts claiming to be from a well-known business - often leading users to fake websites like pharming - these are sent to thousands of people for the few that will believe it. Many email programs or browsers or firewalls have anti-phishing features. Fake emails can be spotted due to bad grammar, requests to follow links or to update personal details.

Answer 53

Watching a persons activity physically (looking at PIN numbers while they're entered, or while entering passwords). Doesn't require technical expertise and can be stopped by being discreet when entering personal details.

Answer 54

When someone makes up a story to get the victim to give information/do things they wouldn't normally, criminals use these tactics to try and pressure/rush people into giving away details without proper thought - reduce risk by using security measures that can't be given away (biometrics).

Answer 55

A set of rules and procedures that an organisation will follow to ensure their network is protected against any possible security threats.

Answer 56

Unique identifiers assigned to network devices by the manufacturer (can't be changed).

Answer 57

When data is translated into a code only someone with the correct key can access, encrypted text is called cipher text and non-encrypted data is called plain text.

Answer 58

Finds/stops malware from doing any damage, may different types, like firewalls - examine all data entering and leaving a network and block any potential threats.

Answer 59

To patch any identified security holes in a piece of software, unpatched/outdated software can be more easily exploited by hackers, malware and viruses.

Answer 60

Controls which parts of a network different users can access, limiting the number of people with access to important data so help prevent attacks from within the organisation.

Answer 61

It checks the MAC address of devices trying to connect to a network and only lets allowed devices join - makes sure the only people on a network are trusted users.

Answer 62

Passwords, biometric measures, email confirmation and CAPTCHA.

Answer 63

Completely Automated Public Turing test to tell Computers and Humans Apart - prevents programs from automatically doing certain things (creating many user accounts).