1.5 Networks Flashcards

1
Q

What are 4 advantages of a star topolgy?

A
  • If one device fails, the rest of the network is unaffected.
  • Very few data collisions
  • Good security ( because all interactions go through the server)
  • Simple to add more nodes
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2
Q

What are 4 disadvantages of a star topology?

A
  • Expensive because of switch and cables
  • It needs experts to set up
  • If the central server or switch fails, the whole network is down
  • Requires a high performance switch or server that all traffic goes through
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3
Q

What are 5 advantages of a mesh topology?

A
  • Very robust network. If one path fails, the rest can still be used
  • There is no central node to fail
  • Excellent for wireless networks
  • It can handle very high data traffic rates
  • Data packets can be sent simultaneously
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4
Q

What are 3 disadvantages of a mesh topology?

A
  • The number of connections increase massively as more nodes are added
  • Impractical for wired network as so many cables needed.
  • Very expensive for a wired network due to cabling and switches needed
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5
Q

What is a network protocol?

A

A network protocol is an agreed way of how to communicate over a network

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6
Q

What should a protocol cover?

A
  1. How the communication between two devices starts and ends.
  2. How the data should be formatted
  3. What the devices should do if data goes missing
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7
Q

Data sent inside a LAN (ethernet) is sent in what units?

A

Frames

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8
Q

Data sent between networks (internet) is sent in what units?

A

Packets

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9
Q

What does TCP stand for?

A

Transmission Control Protocol

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10
Q

Which protocol dictates how data is sent between networks?

A

TCP/IP protocol

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11
Q

2 things TCP does when data is sent?

A
  1. Divides message into packets

2. Adds a sequence number

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12
Q

2 things TCP does when data is received?

A
  1. Spots missing packets and requests for them to be resent

2. Reassembles packets into original data (using sequence number)

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13
Q

What does IP stand for?

A

Internet protocol

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14
Q

2 things IP does when data is sent?

A
  1. Adds destination address to each packet

2. Adds its own address to each packet

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15
Q

What does IP do when data is received?

A
  1. Accepts data packets with its own address

2. Ignores those without its address

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16
Q

Which protocol is used for packet switching?

A

Internet Protocol

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17
Q

What does HTTP stand for?

A

Hyper Text Transfer Protocol

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18
Q

What is HTTP used for?

A

Used by web browsers to access websites and communicate with web servers.

19
Q

What is HTTPS?

A

HTTP but all the information that is sent and received is encrypted.

20
Q

What does FTP stand for?

A

File Transfer Protocol

21
Q

What is FTP used for

A

Transfering files on a network (eg from client to server)

22
Q

What are the 3 email protocols?

A

POP , IMAP , SMTP

23
Q

What does POP stand for?

A

Post Office Protocol

24
Q

What does POP do?

A

POP allows you to retrieve emails from a server to read offline.

It deletes the email once it is downloaded.

25
Q

3 disadvantages of POP?

A
  1. It can only handle 1 mailbox
  2. Messages are deleted once downloaded so can’t be viewed on other devices
  3. It doesn’t support complex searches of emails on the server.
26
Q

What does IMAP stand for?

A

Internet Message Access Protocol

27
Q

What does IMAP do differently from POP?

A

Holds the email until it is actually deleted - you only download a copy

28
Q

2 advantages of IMAP?

A
  1. Allows complex searches to be carried out

2. Allows emails on multiple devices

29
Q

What does SMTP stand for?

A

Simple Mail Transfer Protocol

30
Q

What is SMTP used for?

A

Sending emails and transferring emails between servers.

31
Q

What are the four layers in the 4LM in order?

A
  1. Application Layer
  2. Transport Layer
  3. Internet Layer
  4. (Data) Link layer
32
Q

What is the application layer + 3 examples?

A

Turns data into websites and other applications (HTTP , FTP , SMTP)

33
Q

What happens in the transport layer?

A

TCP divides data into packets and adds sequence number.

Checks data packets are correctly sent and delivered.

34
Q

What happens in the internet layer?

A

IP adds source and destination addresses to packets.

Makes connections between networks.

35
Q

What piece of hardware uses protocols in the internet layer?

A

Routers

36
Q

What happens in the link layer + 3 examples?

A

Protocols resposible for transmitting and receiving data as electrical signals (Ethernet , WiFi , Bluetooth)

37
Q

What are 3 advantages of the 4 layer model?

A
  1. It breaks network communication into manageable pieces which helps developers.
  2. You can recognise roughly what a protocol does by knowing which layer it resides within.
  3. Forces companies to make compatible and universal hardware and software so that different brands work with each other.
38
Q

What is a downside of HTTPS?

A

It is slower that HTTP.

39
Q

3 disadvantages of circuit switching?

A
  1. Very inefficient - once the connection is made, the line is tied up and no one else can use it
  2. Difficult to scale up the network to deal with millions of devices.
  3. Every cable would have to be capable of supporting the maximum bandwidth required
40
Q

What 3 pieces of information are in the packet header?

A
  1. Source Address
  2. Destination Address
  3. Sequence number
41
Q

What happens if some of the packets go missing or are corrupted?

A

The receiving device will send a request for the packet to be resent.

42
Q

What happens when all the data is received and all the CHECKSUMS match?

A

A receipt confirmation is sent to the sending device.

43
Q

What are 3 advantages of packet switching?

A
  1. Robust (if one connection fails there are always other paths)
  2. Each packet contains correction codes, so if a few bits are corrupted, they can be corrected.
  3. Packets can reach their receiving device even if there’s heavy traffic.
44
Q

What are two disadvantages of packet switching?

A
  1. Because packets travel across random paths there is no guarantee that they will arrive within a certain time period (unlike circuit switching which has an unbroken connection)
  2. Packets have to be reassembled and re-sent.