Week 5 - The Internet Flashcards

(38 cards)

1
Q

Describe what the Internet is?

A
  • Gigantic collection of computers.

* Billions of computers connected to the internet.

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2
Q

What is an ISP?

A
  • Internet service provider.

* BT, Virgin, Sky.

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3
Q

How does a business/ university connect to the internet?

A
  • They have a NIC which is directly connected to a LAN inside the business/uni.
  • The LAN is connected to an ISP using high-speed data line/ fibre optic.
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4
Q

How do universities specifically connected to the internet?

A

• After connecting their NIC to their LAN, the uni is connected to JANET which is a network backbone.

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5
Q

What is JANET for uni’s?

A
  • Joint Academic Network

* Network backbone for academic LAN’s.

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6
Q

Who and when was the internet formed?

A
  • Developed by U.S. Department of Defence in 1969.

* Enabled communication over long distance research centres.

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7
Q

What was the first WAN and what was later introduced?

A
  • ARPAnet was first WAN.

* SMTP later introduced for mail.

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8
Q

What was introduced in the early & late 1980’s after the first WAN?

A
  • TCP & IP

* Domain Name System (DNS)

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9
Q

When did the entre for European Nuclear Research release the first WWW software version?

A

• 1992

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10
Q

Describe what interoperable means?

A
  • Computers connected to the internet can communicate with each other.
  • Due to standardised protocols.
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11
Q

What are 2 properties of the internet?

A
  • Easy to use - available to all users.

* Low cost - Cost shared across all users.

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12
Q

What is the Internet Design Principles?

A
  • How to build a system that can handle communication between 2 computers which may:
  • any type of OS
  • connected using any type of network.
  • be at any physical location.
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13
Q
What are the 5 main principles of the Internet Design Principles?
Int
Uni
Lay
Sim
End
A
  • Interoperability
  • Uniform naming & addressing
  • Layering
  • Simplicity
  • End-to-end protocols
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14
Q

What is interoperability in the Internet Design Principles?

A
  • Independent implementations of internet protocols working together.
  • Systems assembled using client & server computers.
  • Buyers & sellers not required to update simultaneously.
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15
Q

What is Uniform naming & addressing in the Internet Design Principles?

A
  • Each device connected must have an IPv4 address.

* IPv6 being introduced.

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16
Q

What is Layering in the Internet Design Principles?

A
  • TCP/IP model

* Each layer does a specific role to send data from user-to-user.

17
Q

What is Simplicity in the Internet Design Principles?

A
  • Hides complexity of levels.

* Applications programmers insulated from complexities of different network devices.

18
Q

What are End-to-end protocols in the Internet Design Principles?

A
  • Interpretation of data happens on the sending & receiving systems.
  • Hides the internal structure of the network.
19
Q

What does the DNS (Domain Name Server) do?

A

• Offer a uniform method of translating IP addresses to human-readable names.

20
Q

What is the TCP/IP model?

A
  • Application (HTML)
  • Transport (TCP/UDP)
  • Network (IP)
  • Link (Ethernet)
21
Q

Describe the link layer in the TCP/IP model?

A
  • Used to route & transport internet traffic.

* Ethernet, token ring, asynchronous transfer mode.

22
Q

What is the physical address?

A
  • Media Access Control

* Unique identifier assigned to most network adaptors or NIC’s by the manufacturer.

23
Q

Describe what hubs are?

A
  • Common connection points for devices in a network (LAN)

* Packet arrives at a hub, it is copied across the LAN.

24
Q

What are 3 problems with hubs?

A
  • Scalability - bandwidth consumed quickly.
  • Latency - Nodes have to wait for moment to transmit to avoid collisions.
  • Network failure - Wrong broadcast speeds interfere.
25
Describe what a switch does?
* Selectively forwards packets between LAN segments. * Forwards data to intended destination. * Uses MAC address to forward data.
26
Describe the network layer of the TCP/IP model?
• Routing & addressing protocols are handled here.
27
Describe what packets are?
* Chunks of data in a numbered order. | * Get sent along different routes to destination.
28
What is the IP (Internet Protocol)?
* Routes packets around the Internet. | * Time to live (exceeded max hops)
29
What does a packet consist of?
* Header - source, destination, error detection. | * Payload - packet data
30
Name 3 examples of control info for packet transmission?
* Header length - size of header info. * Time to live. * Header checksum
31
Describe the purpose of routers?
* Forwards packets to other routers. | * Each router has a local map of networks based off IP addesses.
32
Describe the transport layer?
* Maintains flow control of data & provides for error checking. * TCP used. * Abstraction of reliable byte stream.
33
Describe what the TCP is?
• Establishes initial connection & maintains it for length of connection between two nodes.
34
How does the TCP establish a connection between 2 nodes?
* Sends a request message to destination node containing unique address & port number. * Receiver returns acceptance message containing unique address & port number.
35
What happens if the receiver doesn't respond to the TCP connection message?
• Packets are retransmitted until receiver sends an acceptance message.
36
What is UDP (User Datagram Protocol)?
* An alternative method to TCP. * Is time-sensitive & drops packets that are delayed. * Good for audio & video streaming.
37
Name 2 disadvantages of UDP?
* Doesn't use hand-shaking. * Doesn't guarantee reliable data transmission. * Datagrams may disappear or arrive out of order. * No error checking
38
Describe the Applications layer of the TCP/IP model?
* Supports applications & end-user processes e.g. WWW, email. * Has quality of service, user security, authentication.