Comp Sci practice

World Wide Web (WWW)

A system of linked pages, programs, and files.

The Internet

A global computer network consisting of interconnected networks that use standardized, open (nonproprietary) communication protocols. It relies on TCP/IP for communication between devices.

Computing Network

A type of computing system. It is a group of interconnected computing devices capable of sending or receiving data.

Virtualization

Technology used to allow a computer to have more than one Operating System (OS) present and operating at the same time on a single piece of hardware.

Network

A group of 2 or more computers connected to one another in a way that gives the computer users simultaneous access to the same data, resources, and applications.

Local Area Network (LAN)

Devices connected inside a home, office, building, or small geographic area for LOCAL sharing of resources such as files, printers, applications, etc.

Data Stream

How information is passed through the Internet. They contain chunks of data, which are encapsulated in packets.

Binary

A base 2 numeral system that represents all numbers, using only the two digits 0 and 1.

Byte

Eight bits, able to represent 256 distinct values.

Overflow Error

An error that occurs when a computer attempts to handle a number that is outside of the defined range of values.

American Standard Code for Information Interchange (ASCII)

A standard that computers use to represent letters, numbers, and symbols.

Abstraction

A very common concept in computer science and information technology meaning that a lot of the detail of a system or a process is hidden, allowing the user to focus on the details that are important for the task at hand.

Pixel

A single dot in an image. Many color monitors actually have three dots (red, blue, and green) for each pixel, but it is referred to as one pixel.

Computer Network

A group of interconnected computing devices capable of sending or receiving data.

Computing Device

A physical artifact that can run a program. Some examples include computers, tablets, servers, routers, and smart sensors.

Bandwidth

The maximum amount of data that can be sent in a fixed amount of time, usually measured in bits per second.

Network Path

A sequence of directly connected computing devices that begins at the sender and ends at the receiver.

Packets

Small units of data transmitted on a network. Collected together, they compose some larger data, such as a document, a website, a movie, etc.

Network Interface Card (NIC)

A physical component on a computer or device that provides connectivity to a network.

Media Access Control (MAC) Address

Unique identifier for each networking device, also known as the physical address of a device.

Authoritative Domain Name System (DNS) Server

A server that publishes DNS data for a given domain and its subdomains.

Scalability

The capacity for the system to change in size and scale to meet new demands. The Internet was designed to be scalable.

Cache

Data storage built into a hardware component or computer system to improve speeds by providing memory closer to the point of use.

Latency

Measure of delay in communication between two devices over a network.

Metadata

Information about data, such as when, how, or by whom the data were collected or what software was used to manipulate the data.

Internet Protocol (IP) Address

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

Address Resolution Protocol (ARP)

A tool used by devices on the same network to find the MAC address associated with an IP address.

ARPANET

A network, developed under the direction of the U.S. Advanced Research Projects Agency (ARPA), that interconnected four university computers. It became the basis for the internet.

Transmission Control Protocol (TCP)

A connection-oriented protocol used to send data in a network. It is reliable, keeps track of lost packets, keeps track of packet order, and uses more CPU resources.

User Datagram Protocol (UDP)

A connectionless protocol used to send data in a network. It is a much faster alternative to TCP for sending network traffic but it is unreliable and doesn't keep track of lost packets.

Physical Layer

Concerned with signal propagating from "here" to "there". 1 and 0 - however that may be expressed (light, voltage, radio wave).

Data Link Layer

Makes sense of pulses, the 1s and 0s. Recombines the pulses into collections of data.

Network Layer

Addressing, routing, path finding, collision detection/avoidance. Which path the data takes from "here" to "there".

Transport Layer

Handles synchronization, acknowledgement of sending/receiving.

Session Layer

Breaks data into "chunks" to be transmitted or received across several sessions.

Presentation Layer

Converts data from compressed, encrypted, encoded form into digestible "plain text".

Application Layer

Provides meaning and visualization of data for human (or device) use.

Protocol

An agreed-upon set of rules that specify the behavior of a system.

Payload

The body of a packet.

System Administrator

A person who is responsible for managing computers, networks, servers, and other computing resources for an organization or group.

Redundancies

The inclusion of extra components that can be used to mitigate failure of a system if other components fail. Many of the resources or components serve identical purposes.

Fault-Tolerant

A system designed to work when components fail.

Compression

Storing information using fewer bytes.

Lossless

Method of compression in which original data can be completely recovered from the compressed data, without any loss of content.

Lossy

Method of compression in which data is lost in a way that cannot be recovered from the compressed data.

Uncompress

To extract the original content from compressed data.

Fidelity

The extent to which a copy is identical to the original.

OSINT(Open Source Intelligence Tools)

Any information that can be gathered from free, public sources about an individual or organization. This information must be legally accessible by a member of the public.

Transistor

A miniature semiconductor that regulates or controls current or voltage flow.

Wide Area Network (WAN)

Devices connected across a wide geographic area. Usually, a collection of connected LANs.

Networking

Sharing Information

Server

a computer or computer program which manages access to a centralized resource or service in a network.

OSI Model

A conceptual framework controlled by the International Standards Organization, created to visualize data movement through a network using 7 layers. It provides a standardized model that enables different applications, computer systems and networks to communicate.

DNS Server(Domain Name System servers)

A huge server that maintain lists of all IP addresses and their hostnames that they are associated with

Hub

A device that sends a broadcast message to every system it is connected to.

Switch

A device that sends the message only to the destination device in the LAN like making a local call directly to one person directs signal only to correct device using MAC address.

Router

Sends the message only to the destination device in the LAN or in the WAN.

Hypertext Transfer Protocol (HTTP)

Used when exchanging web page content over the World Wide Web.

Simple Mail Transfer Protocol (SMTP)

Used in sending and receiving email content.

File Transfer Protocol (FTP)

Used when sending and receiving files between a client and a server.

Computer System

A group of computing devices and programs working together for a common purpose.

Wireshark

A network packet analyzer - aka packet sniffer.

Wireless Access Point (WAP)

A switch without wires.

IPv4

The old kind of address but it is still the most commonly used. The format is four decimal numbers separated by dots (dotted decimal notation).

IPv6

The newer but not yet widely used address. Each section is called an octet and can hold a decimal number from 0 to 255 and is separated by colons.

Virtual Port

A number assigned to a specific pathway of communication. Helps manage network traffic by using assigned numbers from 0 through 65535.

3-Way Handshake

Used by TCP to establish a synchronized source-to-destination connection between two PCs.