unit 5: networks Flashcards
what is digital convergence
gradual merger of computing and communications into a new information environment
same information is exchanged among many kinds of equipment, using the language of computers
what is a digital signal
each signal is a bit
0s and 1s, off and on
All the data that a computer processes is a series of 0s and 1s
what is an analog
most phenomena in life are analog
Analog signals use wave variations, continuously changing
Sound, light, and temperature are analog forms
Traditional TV and radio use analog signals
Humans’ vision operates in analog mode
analog data can be converted into digital formed
what is a modem
needed to convert analog data into digital data that computers can use
For data transmission over telephone lines and cables
Modems can convert data by modulating either a analog wave’s amplitude or its frequency
steps of modem transmitting data
- Modems modulate (convert) a computer’s digital data to analog data
- transmit data
- then demodulate (reconvert) it back to digital data for the receiving computer
what is a network
system of interconnected computers, telephones, and/or other communications devices
communicate with one another and share applications and data
what are the benefits of networks
Share peripheral devices, such as printers, scanners, disk drives
Share software
Share data and information
Better communications
Accessing databases
Centralized communications
Security of information, because of improved backup systems
what are the types of networks
wide area networks (WAN)
metropolitan area network (MAN)
local area network (LAN)
wide area networks (WAN)
Communications network that covers a wide geographic area, such as a country or the world
Most long-distance and regional telephone companies
WANs are used to connect local area networks
best example of a WAN is the Internet
use common carrier that is telecommunication company that hires itself for public for communication transmission services
metropolitan area network (MAN)
Communications network covering a city or a suburb
Many cellphone systems are MANs
use common carrier that is telecommunication company that hires itself for public for communication transmission services
local area network (LAN)
Connects computers and devices in a limited geographic area
ex: one office, one building, or a group of buildings close together
basis for most office networks, and the organization that runs the LAN owns it
how are networks structured (two types)
client/server
peer to peer
client/server network structure
clients: computers that request data
servers: computers that supply data
File servers act like a network-based shared disk drive
Database servers store data but don’t store programs
Print servers connect one or more printers and schedule and control print jobs
Mail servers manage email
peer to peer network structure
All computers on the network are “equal”
communicate directly with one another without relying on servers
intranets
use infrastructure and standards of the Internet and the web
for an organization’s internal use only
extranets
milar to intranets but allows use by selected outside entities (suppliers)
VPNs (virtual private network)
use a public network (usually the Internet)
intranets and extranets to connect an organization’s various sites but on a private basis
via encryption and authentication
regular Internet users do not have access to the VPN’s data and information
firewalls
intranets, extracts and VPN use this for security
system of hardware and/or software that protects the system from intruders
network components
all have something in common
wired = twisted-pair, coaxial cable, fiber-optic cable
wireless = infrared, microwave, radio, Wi-Fi, satellite
hosts and nodes
packets
protocols
hosts and nodes
Client/server network has a host computer that controls network
node is any device attached to the network
packets
fixed-length blocks of data for transmission
reassembled after transmission
carries four types of information that will help protocol get to its destination
protocols
set of conventions, or rules
governs the exchange of data between hardware and/or software components in the network; built into the hardware or software you are using
specifies how receiver devices will acknowledge sending devices (handshaking)
specify the type of electronic connections used
specify timing of message exchanges
specify error-detection techniques
what does handshaking in protocols establish
the circuit is available and operational
the level of device compatibility and the speed of transmission
packet’s four types of info to help protocol get to destination
- the sender’s address (IP)
- the intended receiver’s address
- how many packets the complete message has been broken into
- the number of this particular packet.
The packets carry the data in the protocols that the Internet uses—that is, TCP/IP
what are the network linking devices
switch
bridge
gateway
router
backbone
NIC (Network interface card)
NOS (network operating system
switch in network linking devices
Device that connects computers to a network
sends only to intended recipients
operates back and forth at the same time
bridge in network linking devices
interface device that connects same type of networks
gateway in network linking devices
Interface device that connects dissimilar networks
router in network linking devices
Device that directs messages among several networks, wired or and/or wireless
backbone in network linking devices
Main Internet highway that connects all networks in an organization
includes switches, gateways, routers, etc.
NIC (Network interface card) in network linking devices
inserted in a slot on the motherboard
NOS (network operating system in network linking devices
the system software that manages network activity
network topology, what is it
The layout (shape) of a network
what does the network topology include
star
ring
bus
tree
mesh
star in network topology
all nodes are connected through a central network switch
ring in network topology
all nodes are connected in a continuous loop
bus in network topology
all nodes are connected to a single wire or cable
tree in network topology
a bus network of star networks
Mesh in network topology
messages sent to the destination can take any possible shortest, easiest route to reach its destination
must be at least two paths to any individual computer to create a mesh network
ethernet
Network standard for linking all devices in a local area network
describes how data can be sent between computers and other networked devices usually in close proximity
deals with LAN collisions
is a LAN technology that can be used with almost any kind of computer
Ethernet communications protocol is embedded in software and hardware devices intended for building a local area network (LAN)
commonly used in star topologies
