L4 Networking and the Internet

Question 1

When was the telephone invented?

Answer 1

1876: first successful bi-drectional transmission of clear speech by Alexander Bell and Thomas Watson

Question 2

Who is George Stibitz and what did he do in 1940?

Answer 2

1940: first successful transmission of digital data through telegraph wires by George Stibitz (considered to be the father of modern digital computing).

Question 3

What did the telegraph do?

Answer 3

The telegraph enabled messages to be sent by using more code, typically over electrical wires.
Morse code was used to transmit messages globally as a counter attack to the alien invaders.
The start/precursor to computing.

Question 4

Which war did computer technology play an important role in code-breaking?

Answer 4

WW2

Question 5

When was ARPA (Advanced Research projects Agency) established?

Answer 5

1958

Question 6

When did construction of ARPANET (packet-switching network)?

Answer 6

April 1969

Question 7

What is circuit-switching?

Answer 7

If you wanted to call someone, you would phone a telephone operator and ask to be put through to somebody. The operator would physically make the connection on a large plug board (they would pull out a wire and then they would plug it in again, physically making a connection between two telephones.)

Around the 1960s, circuit switching went electronic and switching was performed using relays rather than human operators. It still relied on a physical connection being made between the caller and the receiver.

Question 8

What is the Internet?

Answer 8

Internet is a computer network that interconnects hundreds of millions of computing devices throughout the world so that everyone can have end to end communication

All the devices that are connected to the internet, they are referred to as hosts or end systems
The devices interconnect with two things, communication links and packet switches

Question 9

What are communication links?

Answer 9

These are the connections or pathways that facilitate the transfer of data between different devices or nodes in a network, so it can be guided or unguided

Guided is like a physical medium via which the signals are transmitted
- Open wire
- Twisted pair
- Coaxial cable
- Optical fiber

Unguided is technique that allow transmission of electromagnetic waves through a wireless medium/without using any physical medium
- Microwave transmission
- Radio transmission
- Infrared transmission

Question 10

What is the difference between WWW and the Internet?

Answer 10

The Internet is a global system of Interconnected computer networks.
Carries a vast range of resources and services

WWW is a global collection of documents and other resources accessed through the internet using HTTP - one of many internet communication protocols.
Documents are linked via hyperlinks and are identified by their URL.

Question 11

What are the different types of networks?

Answer 11

LAN - Local area network
Operates within 1km radius
Client-server or peer-to-peer configuration
Can connect multiple LANs to form an intranet

WAN - Wide Area Network
Distances over 1km

The internet
Network of networks that use the TCP/IP

Question 12

What is packet switches?

Answer 12

A route or a path is defined as a sequence of communication links and packet switches traversed by a packet from the sender to the receiver
(A route or a path mean the same thing they are interchangeable terms)
In networking, a concept of a packet is the smallest unit of information that is transported over the network. An email message that you’re sending from your device to another person, that message can be broken down into small units of information that single unit of information is referred to as a packet
Those packets are sent over the network through the routers or the packet switches over the communication links to the receiver

Question 13

What are packet-switching networks?

Answer 13

Data is broken into packets, which are then sent on the best route in the network
Each node on the route sends the packet onto its next destination, avoiding congested or broken nodes

Question 14

How many nodes was ARPANET completed by and what were people able to do on it?

Answer 14

October 1969: ARPANET is completed with four nodes
1973: Norway connects to ARPANET via satellite, followed by London via a terrestrial link

It wasn’t a large network but for the first time across the US and internationally, people were able to sign data and exchange data with one another.

Question 15

What is TCP and IP?

Answer 15

TCP/IP stands for Transmission Control Protocol/Internet Protocol and is a suite of communication protocols used to interconnect network devices on the internet.

(allows computers on the same network to identify and communicate with each other.)

Question 16

What is the timeline from ARPANET to the Internet?

Answer 16

1983: TCP/IP implemented in ARPANET
1990: ARPANET is formally decommissioned

Networks similar to ARPANET sprang up around the USA and in other countries

1984: Domain name system (DNS) implemented
1985: NSFNET was established
1989: Waikato University connects to NSFNET
1991: World Wide Web (WWW) created at CERN by Tim Berners-Lee
1995: NSFNET is retired

Question 17

What are some Networking Hardware?

Answer 17

Connection:
- Wired, e.g. Ethernet
- Wireless, e.g. Wi-Fi, cellular

Network Card:
- Can be built into the motherboard or an expansion card
- Some network cards support wired and wireless connections

To communicate over the internet, a router is required
Router:
- Directs traffic around the network and connects network together(interconnect)
(The general term for a router is a packet switch)

For multiple computers that want to connect to a single network, needs to use another type of packet switch
Switch:
- Used to connect multiple devices to the same network

Router and switch are types of packet switches but they have different functions

Question 18

What’s a modem (modulator/demodulator)? what does it do? and what are the different kinds of modems?

Answer 18

Responsible for transmitting and receiving data on the physical medium

A modem:

• Modulates data from computer/router onto a phone line
• Demodulates signals from a phone line and sends to the computer/router

There are different kinds of modems:
- Dial-up modems up to 56Kbs
- Broadband (DSL - digital subscriber line) modems between 256Kbs to 20Mbs

Question 19

What is protocol?

Answer 19

A protocol is a set of rules that define the format of the message that is being sent, the order of the message that is sent and received and the actions taken on transmission and the received between two communicating devices. So it defines how the connection is opened, how it is terminated, how the data is sent, how it is received and how the communication is ended

Question 20

What is RFC?

Answer 20

(Request For Comments) A document that describes the specifications for a recommended technology.

Many protocols used in networking are defined in a RFC (Request for Comments) document
RFC 791: IP
RFC 2616: HTTP
This is a publication in series that includes specifications and notes about the internet and computing networking technologies.

Question 21

What is RFC 9293: TCP?

Answer 21

RFC 9293: TCP - transports data reliably
Transmission Control Protocol (TCP) is also an important part of the internet. It ensures the packet reaches its destination reliably, if the packet is lost when sending to its destination, then the sender will retransmit the packet, it’s known as error detection.

At the destination or the receiver, TCP will look at the packets and then assemble them in a particular sequence to recreate the original message because the packets may not arrive in order

TCP is used in real time applications like email

Question 22

What is RFC 768: UDP?

Answer 22

RFC 768: UDP
User Datagram Protocol (UDP) is used when users want to send the packets as quickly as possible because UDP does not offer error detection so no retransmission happens if a packet is lost and it also does not offer any flow control, it will send the packets at the fastest possible route it can

UDP is used in real time applications like videoconferencing or audio conferencing because even if lost some packets, it will just not interrupt the communication. So users may not hear certain words or video is not clear but can still communicate. But these days even video conferencing utilizes TCP

UDP: transports data faster but less reliably

Question 23

What is RFC 791: IP?

Answer 23

Internet Protocol (IP) is the main protocol of the internet. It provides each node on a packet switched network a unique identifier and that unique identifier is called the IP address. So it’s like the location of that device on the internet

IP’s job is sending the packet from one host to another host, so every packet will have the IP address

Question 24

What is RFC 2616: HTTP?

Answer 24

HTTP: used for client/server communication such as transferring web pages
(go to lecture 5 for more info)

Question 25

What is an IP address?

Answer 25

a unique string of characters that identifies each computer using the Internet Protocol to communicate over a network.

Every host on the internet needs an IP address, the address is numerical and there are two versions of IP addresses.

Question 26

What are the IP version 4 addresses? (32-bit)

Answer 26

IPv4 addresses are 32-bit numbers that are typically displayed in dotted decimal notation. A 32-bit address contains two primary parts: the network prefix and the host number.

A bit is binary so either it can have a value of one or zero. For 32-bit number is broken down into four groups of eight bits so with one bit can have two values. These are referred to as octets so four octets in an IP version 4 address. Each of the octets are separated by a dot and the dots are used just for humans to read an IP address, it’s not stored in the computer.

Question 27

What are IP version 6 addresses?

Answer 27

These day many more devices connecting to the internet so we have ran out of the IP addresses space and to solve the problem, IP version 6 was proposed. The maximum addresses possible is 2128

Question 28

What is the Internet’s backbone?

Answer 28

• High-capacity fiber optic cables laid on land and under the sea
• Owned by companies who rent out capacity on the cables
• They connect countries together to form the global internet so are extremely important
• Having multiple backbone cable connections provides extra capacity and redundancy

Question 29

What is cloud computing?

Answer 29

The “cloud” refers to tasks and services that are provided over the internet
Cloud computing is the delivery of computing services, including servers, storage, databases, networking, software, analytics, and intelligence over the internet (“the cloud”) to offer faster innovation, flexible resources, and economies of scale.

Question 30

What characteristics of cloud computing?

Answer 30

Resource pooling
Rapid elasticity
Reliability
Measured service
Reduced costs

Question 31

What are the different cloud service models?

Answer 31

IaaS - Infrastructure as a Service
PaaS - Platform as a Service
SaaS - Software as a Service

Question 32

What is IaaS?

Answer 32

Infrastructure as a Service (IaaS) is a type of cloud computing service that offers essential compute, storage and networking resources on demand, on a pay-as-you-go basis

IaaS offers the most control over the resource, and this caters to administrators for hosting and storage solution

Question 33

What is PaaS?

Answer 33

Platform as a Service (PaaS) is a complete cloud environment that includes everything developers need to build, run and manage applications from servers and operating systems to all the networking, storage, middleware, tools and more

PaaS provides less control and caters to developers/software developers for building software

Question 34

What is SaaS?

Answer 34

Software as a Service (SaaS) allow users to connect to and use cloud-based apps over the internet. Common examples are email, calendaring and office tools (such as Microsoft Office 365)

SaaS offers the least control and caters to everyday users

Question 35

What are different cloud deployment models?

Answer 35

Public Cloud:
This refers to cloud services that anybody can utilize, examples are Google Drive, iCloud, OneDrive, Drobox and many more

Private Cloud:
The resources and all the cloud infrastructure dedicated to a sole customer. The user will still be hosting everything through the internet but the server hosting the data will only be the customer’s. Some may opt to use a private cloud for added security while others may use private cloud for performance

Hybrid Cloud:
This use of both public and private cloud, so users can keep certain set of documents in the private cloud but everything else can run on public cloud

Question 36

What is virtualization?

Answer 36

Virtualization is technology that you can use to create virtual representations of servers, storage, networks, and other physical machines. Virtual software mimics the functions of physical hardware to run multiple virtual machines simultaneously on a single physical machine
- Key enabling technology of cloud computing

Question 37

Activity: What network model does the Internet use?

Answer 37

Packet-switching network

Question 38

What internet protocol should your program use if it is time-sensitive?

Answer 38

UDP

Question 39

What is the name of the documents that describe the technical details of protocols?

Answer 39

RFCs