LU4 - Local Area Networks Flashcards

1
Q

Local Area Network(LAN)

A

Networking capabilities of group of computers which are found near each other

  • Nodes - PC’s
  • Network Interface Cards (which network media connects)
  • Connecting devices ( Switches, Repeaters, Bridges)
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2
Q

Bounded Connection Media

A

Network Transmission medium
Signals are confined to the medium and do not leave it

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3
Q

Twisted Pair Cable

A

Consists of 2 insulated strands of copper wire twisted around each other

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4
Q

Unshielded Twisted-Pair(UTP)

A

Widely used

Advantages:
Low cost
Easy to install, expand, troubleshoot

Disadvantages:
Length cannot exceed 100m
Copper cables are inherently weak

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5
Q

Eavesdropping

A

signals travelling copper cable can be intercepted

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6
Q

Attenuation

A

Signal loses strength over a distance

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7
Q

Crosstalk

A

Two cables next to each other, may interfere with each others signals

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8
Q

Electro-magnetic Interference (EMI)

A

Nearby signals from machinery may corrupt signals travelling in copper cables

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9
Q

Shielded twisted-pair (STP)

A

Cable wrapped in protective outer layer

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10
Q

Fibre Optic Cable

A

Carry digital dat signals in the form of pulses of light

Advantages:
Data can be transmitted at very high speed
Data can be transmitted over long distances

Disadvantages:
More expensive than copper cables
Need to be installed by expert

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11
Q

Wireless - Unbounded Connection Media

A

Allow the transfer of data over short and long distances

Useful for long range comms, that cannot be achieved by bounded media

  • Radio Communications
  • Microwave Communications
  • Light, visible and infrared(IR) such as remote controls
  • Electromagnetic induction provides short range communication and power
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12
Q

Near Field Communications(NFC)

A

Provides wireless connection between two devices within close proximity

  • commonly used near payment stations
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13
Q

Radio Waves

A

Type of electromagnetic wave which is known for their use in communication technologies and dat transfer

  • Higher frequency means shorter distance travelled
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14
Q

Point-to-point connection

A

Directly connects two nodes in a network

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15
Q

Broadcast

A

Is a communications channel that is shared by all the devices

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16
Q

Topology

A

The physical setup of a network, way it is connected

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17
Q

Star Topology

A

Cable connect to computer has its other end in a port on central switch

Advantages:
- Easy to setup and maintain
- A problem on one computer does not disturb the rest
- Adding/removing nodes does not affect network
-Most common

Disadvantages:
- A large amount of cabling needed
- Switch adds cost
- If switch fails, network fails

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18
Q

Bus Topology

A

All nodes are connected to a single cable, with terminator at each end to stop signal bouncing

Advantages:
- Requires less cabling than star(Reduces cost)
- No switch needed(less cost)

Disadvantages:
- Faults are difficult to trace since nodes use same cable
- A fault in main cable, can shut down entire network
- Can get Congested

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19
Q

Ring Topology

A

All nodes are connected in a closed loop, data follows around a loop

Advantage:
- Orderly network, each device can transmit
- Each node duplicates data signal, so very little signal degradation occurs

Disadvantages:
- Malfunctioning workstation can cause problem for entire network
- Moves, changes and additions can disrupt network
- slower that star topology

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20
Q

Hybrid Topology

A

A combination of two or more different network topologies

Advantages:
- Reliable as error detecting and troubleshooting is easy
- Effective as it can be suited in building layouts and equipment
- Scalable as size can be increased
- Flexible, can set to needs of organizations

Disadvantages:
- Complex in design
- Costly

21
Q

Ethernet

A

Technology that connects nodes in a local Area Network, establishing communications with each other\

Ethernet Protocol(used to communicate between devices in LAN)

22
Q

IP Address

A

Numerical label assigned to each device, so device can connect to internet

IPv4 (uses 32-bit binary’s to create unique address)

IPv6(Uses 128-bit binary’s to create unique address

(Ip Address Protocol used, to access internet)

23
Q

MAC Address (Media Access Control)

A

Hardware identification number that uniquely identifies each device on the network

(EVERY computer needs MAC Address to be a part of Ethernet LAN)

MAC Addresses(use 48-bit serial number)

24
Q

Internet Protocols

A

How data is transmitted between devices over networks

25
Q

Address Resolution Protocol (ARP)

A

Each device in network has unique MAC Address which needs to be linked to computers IP Address in a ARP table

26
Q

Dynamic Host Configuration Protocol (DHCP)

A

Takes all the manual work out of IP Addressing

When a new device connects to network, the DHCP will assign it an address that is not currently in use

27
Q

Domain Name Server (DNS)

A

Internets equivalent to a phone book

Maintain a list of domain names, and translates them to IP Addresses.

28
Q

Transmission Control Protocol (TCP/IP)

A

Communication protocol for internet,

defines rules that computers must comply with in order to communicate with each other

29
Q

Network Interference Card (NIC)

A

Acts as physical interface or connection between computers and the network cable

(Network cable Connects to card port)

30
Q

Repeater

A

Connects network segments and boosts signal(Over long distances, signals become weak (Attenuation))

31
Q

Bridge

A

Connects network segment, strengthens signal as they pass

Looks at MAC Addresses, only forwards data packet to different network segment if MAC Address is not in the same segment

32
Q

Switch

A

Connects nodes in star topology

  • UTP cable goes into port “SWITCH”
  • Message is sent to switch in the form of a FRAME
  • Switch boosts Signal, sending message to intended node
  • Stores MAC Addresses, so it can easily send frames to matching Addresses
33
Q

Router

A

Sophisticated device that is used to connect different networks that have the same protocols

  • Boosts signals and uses nodes’ IP Addresses to determine best path for dat packets to travel

-Routing gable stores information about networks connected

34
Q

Application, Presentation and Session Layer

A

The application layers Sends the data to layer 6

Presentation Layer translates it into binary and compresses it

When data is downloaded, session layer will determine which packet belongs to which files

(HTTPS, FTP)

35
Q

Transport Layer

A

Receives data from layer 5, breaks it into segments

Each segment has a source and destination port number, as well as sequence number

Port numbers help ensure each segment reaches correct application
- Performs error checking(if missing it will resend)

(TCP and UDP)

36
Q

Network Layer

A

Receives packets from network Layer

The data link layer assigns physical sender and receiver MAC Addresses to dat packet

This forms a data unit called a frame

This layer is embedded in your computers NIC, allows data to be transfered via Local Media

(COPPER WIRE and OPTICAL FIBRE)

37
Q

Physical Layer

A

Converts the binary from upper layers into signals and transmits them over local Media

38
Q

Packet Header

A

Packet Length:
Either fixed length, where other obtain length from header

Synchronisation:
A few bits that help packet match up to the network

Packet Number:
Which packet this is in the sequence of packets

Protocol:
Determines what type of packet is being transmitted (Email, Web Page, Streaming video)

Destination Address:
Where packet is going

Source address:
Where packet came from

39
Q

Payload

A

Body of a packet

This is the actual data that the packet is delivering
If packet is fixed in length, the the payload may be padded with blank information to make it the right size

40
Q

Trailer

A

Sometimes called the footer

Tells receiving device that it has reached the end of the packets data

41
Q

Frame

A

Are created by layer 2 by encapsulating the packet from the network layer as the frames ‘payload’

Frame check sequence:
Used to detect errors that have occurred in data transmission

42
Q

Virtual Local Area Network (VLAN)

A

Is a subnetwork which can group together collections of devices in a LAN to create a new Virtual LAN

  • Helps improve the overall performance of a network by grouping devices that communicate most frequently
43
Q

Wireless LAN

A

Equivalent of wired LAN, with less wires

  • Provide temporary connections to an existing, cabled networks
  • Helps provide backup to an existing network
  • Provides some degree of portability
  • Extends networks beyond the limits of cable connectivity
44
Q

Wireless Access Points

A

Consists of a fixed-position wireless transceiver that broadcasts a signal within an area called a microcell

(Base Station)

45
Q

Hotspots

A

Site that offers internet access over a wireless LAN with the use of of a router or wireless access point connected to ISP(Internet Service Provider)

46
Q

Wireless Bridge

A

A component that offers an easy way to link network segments without using cable

47
Q

Wi-Fi Router

A

Allows multiple computers to join the same network and provides access to internet

48
Q

Wireless Mesh Network

A

Comprises of many wireless nodes with access points that are spread out among hundreds of wireless mesh nodes that ‘link’ to each other to share the network connection across a large area

Advantages:
- Reduced cable cost
- I node fails, the network can self-heal by using another node
- Easy to extend

Disadvantages:
- Increased workload for each node
- Initial setup is complicated