CS > Networks > Flashcards

Networks Flashcards

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1
Q

What is a network?

A

computers which are interconnected for the purpose of exchanging data

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2
Q

What is a protocol?

A

A set of rules that determines how data is transmitted over different computers on the network. They allow devices to communicate with each other regardless of their differences.

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3
Q

What are the ways in which networks are connected?

A

They can be wired(cooper wires, electrical signal) or wireless(radio waves)

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4
Q

What is a LAN?

A
  • Local Area Network
  • Many computers are connected to each other and can share resources
  • shared services
  • Privately owned and operated - provides a secure and controlled environment
  • 1 to 10 km range
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5
Q

What is a WAN?

A
  • Wide Area Network
  • Many LANs joined connected which can communicate with each other
  • Long distance communication (>50km range)
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6
Q

What is a VLAN?

A
  • Virtual local area network* Makes it seem like computers are under one LAN* Can be between different computers in different countries
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7
Q

Why are VLANs implemented?

A

For scalability, security and ease of network management. They can quickly adapt to changes in network environments and relocation of nodes.

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8
Q

What is a SAN?

A
  • Storage Area Network* High speed network that stores and provides access to large amounts of data
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9
Q

What are some features of SANs?| 6 features

A
  • Fault tolerant - one SAN fails, data can stil be accessed* Scalable* Appears as a local drive and not a network drive* fibre channels* Unaffected by network traffic* Expensive
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10
Q

What is a WLAN?

A
  • Wireless LAN* Used to send and receive data* 50 meter range
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11
Q

What is PAN?

A
  • Personal area network* Used for communication with individuals in close proximity* 10 meter range* Bluetooth and Wifi direct
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12
Q

What is P2P?

A

Network model which allows direct exchange of files and data

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13
Q

What is NAS?

A
  • Network attached storage* Storage device on the network* Multiple hard drives* Own NIC* Connects to a router or a switch* If the NAS fails, nodes can not access it
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14
Q

Differences between internet and extranet.

A

Internet* public* less secure* accessible by anyone* large number of users can access it* not owned by anyone* general public uses it* less costlyExtranet* private* secure* username and password required* limited number of users can access it* owned by an organization* employees use it* expensive

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15
Q

What is the OSI model?

A

The open systems intercommunication model is a conceptual model that represents how communication over networks is divided

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16
Q

What are the layers in the OSI model?

A

Application layer, presentation layer, session layer, transport layer, network layer, data link layer and physical layer| “A”ll “P”eople “S”eem “T”o “N”eed “D”ata “P”rocessing

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17
Q

What does the application layer do?

A

It is used by end-user software such as web browsers and email clients. It provides protocols that allow software to send and receive information and present data to users.| e.g - HTTPS, FTP, POP, SMTP, DNS

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18
Q

What does the presentation layer do?

A

It prepares data for the application layer:* Data reformatting to ensure character encoding scheme is correct* Performs encyrption(data can only be decrypted and the destination node)* Data compression

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19
Q

What does the session layer do?

A
  • Creates and manages session till logout* Adds checkpoints(which can be accessed if an error occurs)* Terminates session
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20
Q

What does the transport layer do?

A
  • Takes data from session layer and breaks it into segments* Determines type of connection(TCP or UDP)
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21
Q

What is TCP?

A

Connection oriented protocol which is reliable, slower than UDP and has error correction

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22
Q

What is UDP?

A

Connectionless protocol which is unreliable, faster with no error correction but discards the packets and request to resend instead

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23
Q

What is flow control?

A

The sender and receiver might be sending and receiving at different speeds, but the data is not lost

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24
Q

What does the network layer do?

A

The segments are broken down into packets. The path is selected and the source and destination node IP addresses are added

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25
What does the datalink layer do?
It breaks down the packets into frames(depending on hardware) and sends them. It also adds the MAC address which keeps changing on each node
26
What does the physical layer do?
Converts frames into raw bits(1s and 0s). It decides:* the connector* electric cable or wireless technology* bitrate* mode of communication(uni or bi directional)
27
What is a VPN?
A virtual private network establishes a secure and reliable network connection over an unsecure network such as the internet
28
How does a VPN establish a secure connection?
It encrypts your data and disguises your identity by hiding your IP address.
29
What is tunneling?
An additional layer of protection on each packet added by the VPN.
30
What are some applications of a VPN?
* It provides a secure connection for remote workers* Provides an extra layer of protection for people who access public Wifi* Enable you to access regional restricted internet contents
31
What does the term "data" mean?
Anything in a form suitable for use with a computer e.g binary
32
What does the term "packet" mean?
A small unit of data used in network communication
33
What does a packet contain?
* Source IP address* Destination IP address* Sequence number of packets(original order of packets so they can be reassembled at the destination)* Type of service* Flags* Other technical data* Payload(the bulk of the packet where the actual data is)
34
Why are protocols necessary?| Not "What do protocols do?"
* They ensure interoperability* Provide facility for error detection and correction* Ensure security* Allow efficient communication
35
Why can the speed of data transmission vary?
* Type of connection* Time of delay* Distance* ISP* Cable quality
36
Why is data compression necessary?
* Reducing bandwidth requirements* Improve transmission speeds(less data to transmit hence improved perfomance of the network)* Reduces storage requirements* Reduces cost(costs of bandwidth and storage)
37
Types of cabling?
Twsited pair, coaxial cable and fibre optic cable| refer to the unit 3 notes doc for advantages and disadvantages
38
Types of waves used to create wireless networks?
Radio waves, microwaves and infrared waves
39
Types of network devices?
Hubs, switches, routers, gateways, repeaters and firewalls
40
What are hubs?
* A device which physically connects segments of a network* They have ports to connect the segments* The data sent by one device is passed to all network segments connected to the hub
41
Advantages, disadvantages of a hub?
cheap, affected by lots of traffic and slow data transmission speed
42
What are switches?
* Hardware device which physically connects segments of a network. Ports to allow connection of segments and data transmission* Different layers of switching
43
What are the differences between hubs and switches?
Hub passes data to all segments while switch passes data to a specific segment.
44
What is a router?
* Hardware device which connect networks* Forwards the packet to the next router* Maintains routing table to determine where to send the next packet(protocols OSPF and RIP)* Router and switch are usually combined * works on OSI layer 3
45
What is a gateway?
* A router which allows two networks using different protocols to communicate* Can use software, hardware or combination* Installed on the border of the network* Can incorporate firewall and NAT(network address translator)
46
What is a repeater?
An electronic device that receives a signal and retransmits it at a higher level or higher power or onto the other side of an obstruction so the signal can cover longer distances
47
What is a firewall?
Barrier between secure network and unsecure network(home and internet). It prevents forbidden communication on the network
48
What are the advantages of wireless networks?
* Convenience(resources can be accessed from any location)* Mobility(not restricted by wires)* Productivity(encourages colaboration)* Easy to set up* Easily expandable*
49
What are the disadvantages of wireless networks?
* Expensive to set up* File sharing speed is slower and vary depending on your location(distance between you and the network)* General speed is slower than wired* Obstructed by items(walls, chairs, ceilings, furniture and other electronic devices)* Generally less secure* Cost of failure is high
50
What are the hardware components in a wireless network?
WAP(wireless access point), wireless routers, WNICs and client devices
51
What is a WAP and what does it do?
A device that allows other devices to connect to a network. It acts as a bridge between wired infrastructure and wireless devices
52
What is a wireless router and what does it do?
Combines a router and a WAP. It routes network traffic between local and external network while also providing wireless connectivity
53
What are antennas and what do they do?
Used with access points to broadcast and receive wireless signals.
54
What is a WNIC and what does it do?
Wireless adapters in individual devices that allow them to connect to a wireless network
55
What are client devices?
Wireless enabled devices.
56
What are the software components of a wireless network?
Drivers and firmware.| refer to unit 3 notes for more information.
57
What are the characteristics of wireless networks?
* Wireless communication* SSID(set service identifier) - the network name* Security features(WPA2 or WPA3 encryption, MAC address filtering, password(WPA/WEP) for network access)* Support multiple devices at the same time* Roaming(the ability to switch between access points while maintaining connection)| Some of the advantages and disadvantages are also characteristics.
58
Security features?
* PSK* WEP* WPA2/WPA3* userID* trusted MAC addresses
59
Advantages of encryption?
* Hard to break* Computers can encrypt data on the fly
60
Disadvantages of encryption?
* Users make weak passwords which are easy to guess* Backdoors(methods of bypassing)
61
Advantages of userID?
* Access rights can be set for each user* Groups can be created to manage rights in batches
62
Disadvantages of userID?
* userID can be stolen* system can be bypassed* Does not protect against intercepting messages
63
Advantages of trusted MAC?
* Devices can be controlled* Devices can be linked to a user* Whitelisting prevents unauthorised devices from using the network
64
Disadvantages of trusted MAC?
* Change can be slower* Guest devices must be managed* MAC address can be spoofed
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