Networks (Essentials)

server

computers that are assigned responsibility for certain tasks for the whole network and provide services to other computers

client computer

regular desktop, laptop, or mobile computers that connect to a network to use its services

authentication

the act of identification that network users normally have to use in order to connect to a network (usually via a username and password)

hub

a device that connects computers to a network; most basic/cheapest way to network computers; when it receives data, this device rebroadcasts it to every connected device = wasted bandwidth

switch

a device for connecting computers on a network but can inspect the data and determine the intended destination = saves bandwidth

router

either a wired or wireless device used to connect two or more separate networks (i.e. a school network to the Internet)

peer-to-peer network

type of network with no central server, where every client has equal status; common in homes/small businesses

firewall

Feature of a computer that determines which data is allowed to enter and leave a network

proxy server

a type of server which acts as a middle step between two computers, usually between a local computer and a web server on the Internet

local area network (LAN)

a type of network confined to one geographical area such as a home, office building, or school campus

wireless LAN (WLAN)

a local network in which some or all devices connect wirelessly (ex. often found in schools); requires special security precautions

personal area network (PAN)

a type of network created when a mobile device is connected to a computer; could be connected in a variety of ways like Bluetooth, USB cable, infrared

metropolitan area network (MAN)

a type of network that covers a relatively large area such as a large university campus or city; usually is a series of LANs connected together

wide area network (WAN)

a type of network that covers a large geographical area such as multiple cities or countries; the Internet would be considered to be this type of network; often a network of networks (p. 74; PDF p. 8)

virtual private network (VPN)

a network "tunnel" across a WAN that uses encryption of data to allow users to send information over a public network securely; useful for organizations whose users are often remote and widespread who may connect from less secure locations (p. 75; PDF p. 9)

fiber optic cables

type of wired network connection that transfers data by sending light down an extremely thin glass tube; extremely fast; very expensive; mostly used for huge volumes of traffic (p. 76; PDF p. 10)

cable

type of wired network connection; most common form of broadband Internet access in homes; uses existing cable television network wire and a cable modem; bandwidth can be reduced if many concurrent users on at the same time (p. 76; PDF p. 10)

dialup

a type of wired network connection; relatively old technology; connects computers to a network using a standard telephone line connected to a MODEM; relatively slow; ties up phone line (p. 76; PDF p. 10)

Ethernet

a type of wired network connection that uses a special cable to transfer data at high speed over relatively short distances (usually less than 100 yards); clients must have a network card that supports the speed of the cable (p. 76; PDF p. 10)

Wi-Fi

a type of wireless network connection used to connect devices in a relatively small area such as a office, home, hotel, coffee shop; uses wireless router (p. 77; PDF p. 11)

Bluetooth

a type of wireless network connection that is used for short distances or PANs; often used to connect computers to mobile phones or other devices (p. 77; PDF p. 11)

3G/4G (3rd Generation/4th Generation)

a type of wireless network connection built for mobile phone network; users do not have to use Wi-Fi to access Internet; speed varies greatly depending on signal quality (p. 77; PDF p. 11)

bandwidth

the amount of data a network can transfer at once (p. 77; PDF p. 11)

rates at which bandwidth is measured

bits per second (bps); kilobit (Kbps) = 1,000 bps; megabit (Mbps) = 1 million bps; gigabit (Gbps) = 1 billion bps (p. 77; PDF p. 11)

Media Access Control (MAC) address

a unique number built into virtually every network device; sometimes called hardware address; not designed to be changed but can be spoofed (p. 78; PDF p. 12)

protocol

on a network, a set of rules that defines how computers will communicate on a network (p. 78; PDF p. 12)

Internet Protocol (IP)

a network protocol that governs how devices on a network are identified and how information is routed between them; each machine is assigned a number (an address) like 192.168.1.10 (p. 78; PDF p. 12)

private IP address

a feature of IP addresses which allows computers to be configured with a specific IP address (p. 78; PDF p. 12)

public IP address

a feature of IP addresses which allows routers to assign a secondary IP to a computer so that it may access the Internet (p. 78; PDF p. 12)

Transmission Control Protocol (TCP)

a network protocol that deals with ensuring that data is sent and received correctly; if data is lost, this protocol makes a request for the data to be re-sent (p. 78; PDF p. 12)

ports

in networking software, these are used to identify different network protocols that the computer uses (ex. 80=HTTP, 25=SMTP email, 443=HTTPS) (p. 79; PDF p. 13)

IPv6

a new networking standard for assigning IP addresses; uses 128 bits to assign addresses rather than 32 bits = more addresses can accomodate more things (p. 79; PDF p. 13)

Universal Resource Locator (URL)

a naming convention for an IP address that makes it easier for people to remember (i.e. www.google.com); also called "hostname" (p. 82; PDF p. 16)

domain name

part of a URL, usually referencing a site's full name (i.e. google.com) (p. 82; PDF p. 16)

domain name system (DNS)

system of servers on the Internet responsible for translating domain names into IP addresses (i.e. www.google.com --> 74.125.229.51) (p. 82; PDF p. 16)

DNS poisoning

an attempt to falsify DNS data to commit crimes (p. 82; PDF p. 16)

HyperText Transfer Protocol (HTTP)

a protocol that governs communication between web servers and web browsers (p. 82; PDF p. 16)

HyperText Transfer Protocol Secure (HTTPS)

a version of the http protocol designed to encrypt data for more security; essential for sensitive transactions (p. 83; PDF p. 17)

Transport Layer Security (TLS) or Secure Socket Layer (SSL)

types of encryption used in HTTPS (p. 83; PDF p. 17)

Internet

the physical network of computers across the globe using TCP/IP to operate (p. 84; PDF p. 18)

World Wide Web (WWW)

An often used subset of the Internet, providing access to interlinked web pages. (p. 84; PDF p. 18)

Examples of Internet Services

file transfer protocol (FTP), BitTorrent, VoIP, HTTP, email

Web 2.0

generic term for web sites that allow users to contribute information as well as view it; term helps distinguish it from first web sites which only allowed VIEWING of information

Blog

A website that keeps a chronological list of posts, often used like individual journals; readers can often comment on postings. (p. 85; PDF p. 19)

social network

Web 2.0 technology; designed for people to stay in contact with friends and family; ex. Facebook (p. 85; PDF p. 19)