Protocols ensure that a single path between two computers is established before sending packets over it.

Routers are hierarchical and the "root" router is responsible for communicating to sub-routers the best paths for them to route internet traffic.

A packet traveling between two computers on the Internet may be rerouted many times along the way or even lost or "dropped"

Protocols ensure that a single path between two computers is established before sending packets over it.

Routers act independently and route packets as they see fit.

Routers are hierarchical and the "root" router is responsible for communicating to sub-routers the best paths for them to route internet traffic.

TCP/IP relies on HTTP

HTTP relies on TCP/IP

TCP/IP relies on DNS

DNS relies on HTTP

TCP/IP relies on HTTP

DNS relies on TCP/IP

TCP/IP relies on DNS

DNS relies on HTTP

High level protocols take into account specific implementation details of lower level protocols to ensure they are compatible.

Low level protocols can provide functionality to high level protocols without revealing the details of how this is accomplished.

High level protocols can take on the role of a low level protocol in the event of failure in the system.

Low level protocols are written in binary while high level protocols are written in hexadecimal

about.example.com

example.co.uk

example.com.org

example.org

Packets are numbered so if they arrive out of order the message can be reassembled.

TCP guarantees that no packets are ever dropped

Packets can be routed on different paths from sender to receiver.

Messages are broken into packets to improve reliability of the internet

An International coalition of government agencies who oversee the Internet in their countries.

A collection of the leaders of the Tier 1 Internet service providers.

A loosely organized collection of citizens and engineers.

Political leaders and heads of state.

It asks a DNS server for the corresponding IP address

It scans addresses until it finds the one it's looking for

It uses a Border Gateway Protocol to get the address from a nearby computer.

It creates an IP address for the domain, and shares it with the closest DNS.

32-bit addresses could not accommodate the increased size and amount of data traveling on the Internet as it has grown in popularity

IPv6 will allow problems with IPv4's address hierarchy to be resolved

IPv4 proved unreliable in some cases where network redundancy could not be ensured

32-bit addresses could not ensure that every internet-connected device can receive a unique IP address

TCP

DNS

HTTP

URL

Net Neutrality

Protocol

Abstraction

Latency

Abstraction

Net Neutrality

Protocol

Latency

Octal Number System

An example of lossless compression is a .jpg file

Lossless uses inexact approximations while lossy does not·

You can completely reconstruct lossless but not lossy compression ·

You can completely reconstruct lossy but not lossless compression

Width and Height of an Image

Type of Compression

Number of Colors

Resolution

1 Terabyte = 1,000 kilobytes

1 Petabyte = 1,000 Terabytes

1 Megabyte = 1,000 bytes

1 Terabyte = 1,000 gigabytes

A .jpg (JPEG) file is typically measured in megabytes

The entire amount of information transferred over the entire Internet is typically measured in terabytes

A .txt file is typically measured in kilobytes

An .mov file is typically measured in gigabytes

25 MB

250 MB

2.5 MB

25,000 MB

Yes, all this data will fit on the thumb drive

No, The data will not fit on the thumb drive

simplistic

heuristic

abstraction

1,250 bytes

3,774 bytes

3,750 bytes

249 bytes

Data compression is only useful for files being transmitted over the Internet

Regardless of the compression technique used, once a data file is compressed, it cannot be restored to its original size.

Sending a compressed version of a file ensures that the contents of the file cannot be intercepted by an unauthorized user.

There are trade-offs involved in choosing a compression technique for storing and transmitting data.

The saved image files were compressed with a lossy compression technique.

The saved image files were compressed with a lossless compression technique.

The saved image files were not compressed properly.

Some information is lost every time a file is saved on a computer.

When the problem can be solved in a reasonable time and an approximate solution is acceptable

When the problem can be solved in a reasonable time and an exact solution is needed

When the problem cannot be solved in a reasonable time and an approximate solution is acceptable

When the problem cannot be solved in a reasonable time and an exact solution is needed

F00

00F

FF00

FF0001

Lossy Compression

Lossless Compression

FFT Compression

Tailored Compression

Lossy Compression

Lossless Compression

FFT Compression

Tailored Compression

1,000 times bigger

10,000 times bigger

100,000 times bigger

1,000,000 times bigger

megadata

superdata

metadata

predata

Ambiguities in natural language necessitate the creation of programming languages for controlling a computer

Compared to the number of words in a natural language, the number of defined words in a programming language is very small.

The number of defined words in a programming language is about the same as the number of words in a natural language.

There are typically many possible ways to interpret an instruction written in a programming language.

Functions are reusable programming abstractions.

Functions help reduce the complexity of writing and maintaining programs.

Functions cannot make calls to other functions within the same program.

Once defined, a function can be called many times from different parts of a program.

Functions help break a problem into logical chunks.

A function name should indicate how long the function takes to run.

Two functions with similar behavior should be given identical names to indicate the relationship between them.

A function name should be as descriptive as possible to indicate what the function does.

Function names should be organized alphabetically.

The function name should begin with a number that indicates the order in which it should be executed.

A function can change names over the course of a program.

Code can be added or removed dynamically from a function while the program is running.

Functions can be called using different names depending on where in the program they are called.

Two functions can be given identical names as long as their code is identical.

Two functions in a single program can have different names but contain identical code.

Top Down Design

Function

Variable

Review Lesson 6 on Code.org

Review Lesson 6 on Code.org

drawStar

drawStar();

function drawStar (){

for(var i=0; i <5; i++) {moveForward(100); turnLeft(36):}}

function drawStar;

function drawStar();

Loop

Function

Loop

Function

Loop

Function

Loop

Function

Parameters determine the number of times the function will run.

Parameters allow for more flexible, generalized behaviors in functions.

Parameters are useful for teams of programmers because they help define the boundaries of the problem they are trying to solve.

Parameters change the order of operations within a function.

Team members can rely on one another to explain their code.

Programmers can write functions without needing to know what they do or how they should work.

Programmers can use functions created by their partners, relying on the functionality without needing to know the specific details of how the function is implemented.

In order for programmers to work together, they must work in the same room.

Abstraction allows programmers to brainstorm more creative solutions to problems.

You need to know how to do this. Review Lesson 9

You need to know how to do this.Review Lesson 9

It represents how computers interpret electrical signals

Because we like to make you do extra maths ;-D

It takes fewer digits to represent a number

Because it describes star systems

Binary is more flexible than other number systems and allows better representations.

It's easier, cheaper and more reliable to distinguish between 2 states of data.

It typically takes less digits to represent data in binary than other number systems.

Binary is the only way to build a machine.

2 bits

3 bits

5 bits

6 bits

At one of the lowest levels of abstraction, all digital data can be represented in binary using only combinations of the digits zero and one.

Some large numbers cannot be represented in binary and can only be represented in decimal.

Groups of bits can be used to represent abstractions, including but not limited to numbers and characters.

The same value (number) can have a different representation depending on the number system used to represent it.

Remove a bit from customerID to make room for incoming customers.

Double the number of bits in customerID to double the number IDs that the database can represent.

Add a bit to customerID to double the number of IDs that the database can represent.

Keep using the 10-bit number for customerID but reserve the first bit to indicate old or new customers.

Bit-rate (bandwidth) is the time elapsed between the transmission and receipt of a piece of digital data.

Digital data can only be transmitted between two devices when they are physically connected to one another (for example by a copper wire)

Latency is the amount of data (measured in bits) that can be sent in a fixed amount of time.

Two devices must communicate using the same bit-rate to successfully send and receive digital data.

2¹ = 2 times as many values

2² = 4 times as many values

2³ = 8 times as many values

2⁴ = 16 times as many values

Symmetric

Asymmetric

Public key

SSL

Moore's Law describes a relationship of boolean logic statements involving AND and OR

Moore's Law is the principle that one should assume that any traffic on the Internet is insecure

Moore's Law is the observation that computing power tends to double every two years

Moore's Law explains why cracking modern cryptography is a "computationally hard" problem

The sender's public key

The sender's private key

The recipient's public key

The recipient's private key

Router to router based on the Travelling Salesman algorithm

Along the same path to stay in order

Timed to arrive at the destination in their correct order

Along a variety of different paths

Attacks that use frequency analysis to break passwords

Attacks that check each possible solution to break encrypted data

Attacks against DNS servers to enable DDOS attacks

Attacks on firewalls to gain access to a company's sensitive data

Sending and receiving information from the web

Encrypting data

Decrypting data

Encrypting and decrypting data

The frequency that data can be transmitted across the Internet

The speed that data can be sent through the Internet

The amount of data that can be transmitted in a fixed amount of time

The delay between the request and the receipt of information on the Internet

To translate natural language website names to their IP address.

To create a new IP address for a website each time it is requested.

To position the packets in the correct order.

To route the Internet request on the way to its destination.

By people clicking on an infected file

From pop up ads

Through network worms

From random botnet attacks

HTML.

HTTP.

DNS.

TCP/IP.

It's the plural of http - a more robust version of http that runs on multiple channels.

s is for "secure" - a version of http that is encrypted.

s is for "simple" - a simplified version of http that runs faster on modern computers

s is for "standard" - to distinguish the original http from non-standard versions like httpv and httpx

DDoS Attack

Phishing Scam

Virus

SSL/TLS layer

Through the ability for additional networks and routers to be added without impacting service.

Through the ability to add longer public keys to keep data secure

Through the ability to add additional authentication for users

Through the ability to add additional latency to requests

0

5

15

20

A secret word only know by Caesar.

The number of characters to shift each letter in the alphabet.

The letter that occurs most often in the encrypted message.

The day of the month that the encrypted message was sent

...people's access to computing and digital technology increases over time through a process of dividing and growing quickly - it is often likened to the biological processes of cell growth

...people's access to computing and the Internet differs based on socioeconomic or geographic characteristics.

...people's access to computing technology is affected by the fact that newer devices that use new protocols makes it more difficult for them to communicate with older devices and technology

...the amount of data on the Internet is growing so fast that the amount computing power and time we have to process it is lagging behind

Public key encryption is an encryption method which relies on separate keys for encrypting and decrypting information.

Public key encryption is a highly secure encryption scheme that in which a single shared key is used by both the sender and receiver of the message.

Public key encryption makes use of certain types of problems which are easier for humans to solve than computers.

Public key encryption makes use of mathematical problems which no algorithm can be used to solve.

That a dataset is larger than 5TB which is the common "Big Data" threshold.

That there is so much data it's virtually impossible to process.

There is enough data that traditional data processing applications are inadequate.

It implies that the findings from the data are potentially hugely important for society.

Through the use of symmetric keys

Through certificates issued by Certificate Authorities (CAs) that validate the keys used

Through the use of double authentication methods

The the use of frequency analysis

No, public key encryption allows the credit card information to be read by the public.

No, the internet protocols are open standards and thus everything sent over the internet is sent "in the clear".

Yes, public key encryption is built upon computationally hard problems that even powerful computers cannot easily solve.

Yes, public key encryption is secure because it transmits credit card information in binary.

9 MOD 8

1 MOD 16

52 MOD 32

9 MOD 64

A key for decrypting is never made public

Using public key guarantees that only the intended recipient can decrypt the message

A Public Key database ensures 3rd party accountability of security

Allows secure communication without establishing a *shared* encryption key ahead of time.

Maintaining privacy of the information stored in the data set.

Scalability of the system.

Structuring the metadata of the information for analysis.

The frequency of a particular item occurring in a data set.

A coordinated effort by a group to simultaneously attempt to gain entry to foreign government's servers or systems

An effort by network engineers to focus all systems on catching a user or computer that has illegally gained access.

An attempt to compromise a single target by flooding it with requests from multiple systems.

An attempt to harass or extort all customers of one or more Internet Service Providers (ISPs).

You accidentally run a piece of code that automatically spreads from one computer to another, exploiting a common vulnerability

You get an email from the IT support desk that asks you to send a reply email with your username and password to verify your account

You get an unwanted email trying to sell you a low quality product or service that seems "fishy."

You accidentally install a piece of software that monitors your activity to steal personal information like your passwords, date of birth, social security number, etc.

I only

II only

I and II

Neither I nor II