00 - Introduction to IT | Cheatsheet

Question 1

CU

Answer 1

Control Unit (CU)
The Control Unit (CU) on a CPU receives information from the software; then, it distributes and directs the data to the relevant hardware components.

Some functions of the CU:
- Determine what/where the next instruction must go for processing
- Send clock signals to all hardware to force synchronous operations
- Send memory taskings if appropriate

Question 1

BNS

Answer 1

Binary Numbering System
The binary numbering system is built on a base of 2. Every time we reach a power of 2, we add another digit. The decimal system works the same way, just with 10.

Question 2

ALU

Answer 2

Arithmetic and Logic Unit (ALU)
An Arithmetic Logic Unit (ALU) is a digital circuit used to perform arithmetic and logic operations. It is the fundamental building block of the CPU.

Some ALU functions:
- Addition & subtraction
- Determining equality
- AND/OR/XOR/NOR/NOT/NAND logic
gates and more!

Question 3

Registers

Answer 3

Registers
A register is a volatile memory system that provides the CPU with rapid access to information it is immediately using.

Functions of a register:
- Store temporary data for immediate processing by the ALU
- Hold “flag” information if an operation results in overflow or triggers other flags
- Hold the location of the next instruction to be processed by the CPU

Question 4

CPU

Answer 4

The CPU
A Central Processing Unit (CPU) is the electronic circuitry that executes instructions based on an input of binary data (0’s and 1’s). The CPU consists of the Control Unit (CU), the Arithmetic and Logic Unit (ALU), and registers (Immediate Access Store).

Question 5

RAM

Answer 5

Random Access Memory (RAM)
Random Access Memory, or RAM, is additional high-speed memory that a computer uses to store and access information on a short-term basis.

Question 6

Latency

Answer 6

Latency Measure
Latency is the amount of delay before that transfer of data begins.

Some common latency numbers:
- Read from solid state drive: 150 microseconds
- Ethernet connection: 10 milliseconds
- 4G connection: 80 milliseconds
- Satellite connection: 900 milliseconds

Question 7

Hard Disks

Answer 7

Hard Disks
Hard disks, or hard drives, are responsible for the long-term, or secondary storage of data and programs.

Question 7

Main Computer Functions

Answer 7

Main Functions of a Computer
There are four main functions of a computer that make user interaction possible:

Input
Processing
Memory
Output

• Input is data we give to our computers through interactions
• Processing is comprised of the translation of input and the instructions given for output
• Memory is used to store either temporary or permanent information
• Output is the information that gets returned by the computer

Question 8

Throughput

Answer 8

Throughput Measure
Throughput is the total amount of data that can be transferred in a given amount of time.

Some common throughput numbers:
- Smartphones: 500MB/Sec
- Desktop drive: 5,000MB/Sec
- RAM: 20,000MB/Sec

Question 9

The Mainboard

Answer 9

The Mainboard
The mainboard, or motherboard, is a printed circuit board that houses important hardware components via ports.

Question 10

Ports

Answer 10

Ports
A port is a physical outlet used to connect devices to a computer. A computer typically contains multiple ports. This connection allows for communication between the IO device and the computer.

Question 11

OSI Model

Answer 11

OSI Model
The OSI Model is a conceptual, implementation-neutral model that describes networking in seven separate layers, where each layer covers a set of functions and tasks.

This model helps us communicate while we do network troubleshooting and architecture.

Question 12

Network Protocols

Answer 12

Network Protocols
A network protocol is a set of standards for Internet traffic.

Among them are the big transport protocols:

1. TCP and UDP
2. HTTP for web requests
3. DNS to convert domain names to IP addresses
4. IMAP/POP3 for email
5. SSH
6. FTP
7. SMB for access to specific resources

Question 13

TCP/IP Model

Answer 13

The TCP/IP Model is an implementation-specific networking model that revolves around the TCP protocol and IP addressing which anchor the Internet as we know it.

Its layers include:

The Network Layer
The Internet Layer
The Transport Layer
The Application Layer

Question 14

OSI Layers

Answer 14

The OSI layers include: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

1. The Physical layer includes physical technologies
2. The Data Link layer includes data framing and local MAC addressing
3. The Network layer includes connecting to the larger web and IP addressing
4. The Transport layer includes protocols that make sure reliable delivery happens
5. The Session layer authenticates and maintains communication over a period of time
6. The Presentation layer en/decrypts and translates data into presentable form
7. The Application layer includes all the applications we interact with that render data

Question 15

Network

Answer 15

Network
A network is two or more computers or devices that are linked in order to share information.

Networking refers to a large set of standards and protocols that organize and regulate the sharing of information.

Question 16

Network Categories

Answer 16

Three broad categories of networks include:

Local Area Network (LAN), a smaller-sized network that connects multiple devices in a small area

Campus Area Network (CAN), a larger network that connects multiple computers and devices over a slightly larger area

Wide Area Network (WAN), the largest-sized network that connects multiple computers, over a geographically large area

The Internet is technically a WAN.

Question 17

The Internet

Answer 17

The Internet
The internet refers to the actual network of connected computing devices.

Question 18

The World Wide Web

Answer 18

The World Wide Web
The world wide web is a collection of interlinked websites and other web resources that use the internet to share data.

www.

Question 19

The Client-Server Model

Answer 19

The Client-Server Model
The client-server model describes how the flow of data is transferred on the internet.

Question 20

Web 2.0 Applications

Answer 20

Web 2.0 applications provide a dynamic user experience by:

1. Responding to user input without having to reload the page
2. Emphasizing user-generated content and social sharing.

This was made possible through technical advances such as JQuery and web frameworks.

Question 21

Mobile Internet Traffic

Answer 21

Mobile Internet Traffic
Mobile internet traffic accounts for more than half of all internet traffic and has caused web development practices to provide a good user experience regardless of device type.

Question 22

Responsive Web Design

Answer 22

Responsive Web Design
Responsive web design allows the presentation of websites to adjust based on the size of the window in which they are displayed.

Question 22

Mobile Application Connection

Answer 22

Mobile Application Connection
Mobile applications are not a part of the world wide web although most of them are connected to the internet.

Question 23

TCP/IP

Answer 23

TCP/IP
Transmission Control Protocol and Internet Protocol (TCP/IP) are standards for data transfer which allow networks all over the globe to communicate with each other.

Question 24

The Operating System

Answer 24

The Operating System
The operating system (OS) is system software that manages the basic functionalities of a computer and is responsible for tasks such as process management, memory management, file system management, IO management, networking, security, and providing a user interface.

Question 25

Filesystem

Answer 25

Filesystem
The filesystem is the data structure used by the operating system to store and retrieve data.

Question 26

Filesystem File

Answer 26

Filesystem File
A file is a unit of storage used to describe a self-contained piece of data and can have a variety of possible formats based on what that file contains.

Question 26

Filesystem Directory

Answer 26

Filesystem Directory
A directory is a data structure that contains references to files and other directories. They are typically organized in a hierarchical tree structure called a directory tree.

Question 27

Working Directory

Answer 27

Working Directory
A working directory, also called a current directory, is the directory associated with the execution of a process.

Question 27

File Attributes

Answer 27

File Attributes
File attributes are a collection of metadata that determine how files behave, such as if they are hidden or compressed.

Question 28

File Permissions

Answer 28

File Permissions
File permissions determine which users and groups can read, write, and execute the file.

Question 29

File Control Block

Answer 29

File Control Block
A file control block contains the metadata for a file, such as permissions and access times.

Question 30

Pseudocode

Answer 30

Pseudocode
Pseudocode is a description of an algorithm using everyday wording, but molded to appear similar to a simplified programming language.

EXAMPLE
define password
create a pass_length variable and set it to 0
create a contains_number variable and set it to False
if the entire password hasn’t been searched:
iterate to the next character of the password
increment the pass_length variable
if the current character of the password contains number:
set contains_number to True
if pass_length is greater than 8 and if contain_number is equal to True:
valid password
otherwise:
invalid password

Question 30

Flowchart Shapes

Answer 30

Flowchart Shapes
In code-based flowcharts, common ANSI shapes are:

1. ovals for terminals
2. arrows for flowlines
3. rhomboids for inputs and outputs
4. rhombuses for decisions
5. rectangles for processes.

Question 31

File and Directory Operations

Answer 31

File and Directory Operations
Both files and directories can be created, opened, read, written, deleted, closed, linked, unlinked, listed and truncated. It is possible to move across directories as well as find files within directories.

EXAMPLE
/ Create a file named lunch
touch lunch

// Write a list of foods to the lunch file
echo “burger, salad, and sandwich” > lunch

// Read the file
cat lunch

// Delete the file
rm lunch

// Make a directory named dinner
mkdir dinner

// List the files in the dinner directory
ls dinner

// Delete the directory
rm -r dinner

Question 32

Filesystem Layers

Answer 32

Filesystem Layers
The filesystem has multiple layers of abstraction:

1. The application programs
2. Logical file system
3. File-organization module
4. Basic file system
5. IO control
6. Devices.

Question 33

Column Constraints

Answer 33

Column Constraints
Column constraints are the rules applied to the values of individual columns:

1. PRIMARY KEY constraint can be used to uniquely identify the row.
2. UNIQUE columns have a different value for every row.
3. NOT NULL columns must have a value.
4. DEFAULT assigns a default value for the column when no value is specified.

There can be only one PRIMARY KEY column per table and multiple UNIQUE columns.

EXAMPLE
CREATE TABLE student (
id INTEGER PRIMARY KEY,
name TEXT UNIQUE,
grade INTEGER NOT NULL,
age INTEGER DEFAULT 10
);

Question 34

CREATE TABLE Statement

Answer 34

CREATE TABLE Statement
The CREATE TABLE statement creates a new table in a database. It allows one to specify the name of the table and the name of each column in the table.

EXAMPLE
CREATE TABLE table_name (
column1 datatype,
column2 datatype,
column3 datatype
);

Question 35

INSERT Statement

Answer 35

INSERT Statement
The INSERT INTO statement is used to add a new record (row) to a table.

It has two forms as shown:

1. Insert into columns in order.
2. Insert into columns by name.

EXAMPLE
– Insert into columns in order:
INSERT INTO table_name
VALUES (value1, value2);

– Insert into columns by name:
INSERT INTO table_name (column1, column2)
VALUES (value1, value2);

Question 36

DELETE Statement

Answer 36

DELETE Statement
The DELETE statement is used to delete records (rows) in a table. The WHERE clause specifies which record or records that should be deleted. If the WHERE clause is omitted, all records will be deleted.

EXAMPLE

DELETE FROM table_name
WHERE some_column = some_value;

Question 37

ALTER TABLE Statement

Answer 37

ALTER TABLE Statement
The ALTER TABLE statement is used to modify the columns of an existing table. When combined with the ADD COLUMN clause, it is used to add a new column.

EXAMPLE
ALTER TABLE table_name
ADD column_name datatype;

Question 38

CIA Triad: Confidentiality

Answer 38

CIA Triad: Confidentiality
In Cybersecurity, Confidentiality is the pillar of the CIA triad which refers to the principle that only those who should have access to information can access it.

Question 38

UPDATE Statement

Answer 38

UPDATE Statement
The UPDATE statement is used to edit records (rows) in a table. It includes a SET clause that indicates the column to edit and a WHERE clause for specifying the record(s).

EXAMPLE

UPDATE table_name
SET column1 = value1, column2 = value2
WHERE some_column = some_value;

Question 39

CIA Triad: Integrity

Answer 39

CIA Triad: Integrity
In Cybersecurity, Integrity is the pillar of the CIA triad which refers to the principle that data is what we expect it to be.

In other words, data should not be able to be edited by unauthorized parties.

Question 40

CIA Triad: Availability

Answer 40

CIA Triad: Availability
In Cybersecurity, Availability is the pillar of the CIA triad which refers to the principle that data is reliably available.

Question 41

Threat Intelligence

Answer 41

Threat Intelligence
In Cybersecurity, threat intelligence is the continuous gathering of knowledge of possible attacks.

Question 42

Risk management

Answer 42

Risk management
Cyber risk management is an ongoing process of identifying, analyzing, and remediating your organization’s cybersecurity threats.

Some of the key components include:

1. Development of policies and procedures
2. Identification of emerging risks
3. Testing of the overall security posture
4. Documentation of vendor risk management.

Question 43

Security Principle: CIA Triad

Answer 43

Security Principle: CIA Triad
One of the most important security principles is the CIA triad, which stands for Confidentiality, Availability, and Integrity.