1a collection of computer equipment that's connected with wires, optical fibers, or wireless links. The various separate devices can communicate with one another and exchange information.
Computer Networks
2latency in a network
ping
3reduces costs as a result of resource sharing
- sharing hardware/peripherals
- sharing apps
- sharing files between entowrk users
- sharing a single network connection
Benefits of Networks
4Hackers/Security
Viruses
Network Failure
Setup costs
Tech support & maintenance
Disadvanatges of Networks
5Hacker Activities
Hacker Access
1. Directly (physically on your computer, has your password, etc.)
2. Via logical ports (not a physical port (usb, hdmi), but through email, etc.)
Trojan horses
- appear useful
- back-door; take over control
Denial of Service
Dsitributed DOS
- comes from multiple PCs
- Harder to trace
6LAN - Local Area Network
- within a small area such as a building or a campus
WAN - Wide Area Network
- covers a much larger geographic area, such as a sate, or a country
Ex. Internet - largest WAN
Network Classifications
7PAN - Personal Area Network
- interconnection fo your personal digital devices
MAN - metropolitan area network
- public high-speed network with range of about 50 miles; covers a town or a city
Additional Classifications
8node
any device that's connected to a network
Ex. laptops, desktops, smartphones
9redundancy
multiple routes or paths leading to the same destination in a network
alternative way for data to be transferred
- more redundancy, the better
10IEEE - Institute of Electrical and Elctronic Engineers
- creates the standards
- project 802 - "local network standards"; family of standards; protocol
IEEE 802 refers to a family of IEEE standards dealing with local area networks
LAN Standards
12Clearly defined rules/standards
- how devices communicate with one another
how data is packaged in messages for sending and recieving
Common Network Protocols
TCP - transmission control protocol
IP - internet procotol
HTTP (S) - hypertext transfer protocol
FTP - file transfer protocol
SMTP - simple mail transfer protocol
Network Protocols
13802.3 - standard for ethernet networks
developed in the 1970s
most efficient, reliable, and fast
standard of how connected computers send data
Ethernet Networks
141. transmission media
- cables, radio waves
2. network adapters
- communication between "nodes" and the network
3. network naviagtion devices
- move data around network
4. software
- NOS (network operation system)
Main Components of Networks
15Network Interface Card
NIC stands for...
16hardware device enabling communication between entowrk "nodes"
- external devices/USB
- intenral devices (expansion cards)/NIC
Network Adapters
17Nodes - any hardware device that is connected to a netowrk; devices may include
- router - transmits data between networks
modem - connects network to ISP (shortform of modulate-demodulate)
switch - transmits data along only 1 network
hub - common connection point for multiple devices on a network
Today most routers funcation as combinations of router and switch/hub
Network Devices
18Packet switching - data is broken into "packets" & sent over shared routes at the same time. Packets are reassembled by the receivbing computer
Circuit switching - both parties need to present at the same time
Ex. phone call, zoom call, etc.
Communication
19Synchronous
- both the sender and reciever are communication in real time
Ex. zoom call
Asynchronous
- sending and receiving messages at different times...not in real time
Ex. recorded lectures, email - can be done whenever without both parties being there
Types of Communication
20"Design"
Peer-to-peer- locally controlled (every computer is equal, no one computer is a server)
Client/server - centrally controlled (probably has an administrator or IT department that controls the server/network)
Network Architectures
21Peer-to-peer
- no "file server" - each PC is equal
- easy to set up
- suitable for a small number of computers
- home networking
Networks
221. power line - uses home electrical wiring
2. phone line - uses conventional phoen lines
ethernet - use proctol for communcation between ndoes, costly, efficient - retransmits until the data is successfulyl sent
wireless - use radio wabves and follow IEEE stands
"Wifi" wireless fidelity
Major difference is the transmission media
Peer-to-peer netwrok types
23Cleitn/server
- has "file server"
- high capacity/speed computer
- contains the NOS
- clients make requests of the server
suitable for larger installations
the internet
24Cloud Netwokr
avoid large capital expednitruees on hardware
scalable - available on demand
maintenance fee
efficient
25Wired Networks Topologies
The arrangement of nodes in a network is referred to as its physical topology
- star, ring, bus, mesh, tree
26Wireless Networks
Radio waves, not cablings
Wi-Fi - connect through "hotspot"
- Several IEEE standards (802.11)
Wirleess network adapte r
- transceiver (combo of TRANSmitter and reCEIVER)
device designed to connect computers or electronic devices within a network, allowing them to transmit and receive messages
27Speed of Transmission
Bandwidth - represents the measure of computer network speed (Ex. width of a highway - the wider the highway, the more cars can pass through at one time)
latency - refers to delays incurred in processing data. low latency is desirable
rate od data transmission between nodes is measured in Gbps
(1 gigabit = 1 billion bits)
28Firewall Network Protection (think of a wall between apartments that slow down or stop fires from spreading from one area to the next)
Software
- port protection (stops hackers from accessing virtual ports)
It's like...locking your doors and windows protects against burglars
Hardware
- Firewalls can be hardware or software
protects your network from the outside work, similalr to a firewall between rooms in a building
29VPN - virtual private network
Protects you from hacking, may slow down browsing
30Computer Threats
Malware
- malicious software
spyware
adware
phishing - when someone fishes or baits you into giving them information
pharming - redirects searches into another destination
DOS - Denial of Service ---------------------- | Makes it so a device is left unusable
DDOS - Distributed Denial of Service -----| - A DDOS attack is a cyber-attack from multiple systems on a server, service, website, or network, flooding it with Internet traffic
ransomware
botnets/zombies - robot networks (networks that have been taken over by hackers and left useless)
worms - takes up network bandwidth; they don't steal you information but slow down the network (Not considered a virus)
trojan horses - program that appears to be useful but is actually a program that allows for a backdoor for hackers
cookies - text files that websites put on your harddrive without your knowledge; holds information that can be used for next time that same website is used)
31Internet & WWW
The Internet came first (before the Web)
The Internet is hardware
The World Wide Web (WWW) was invented on 1989 - 1991. The WWW is the part of the Internet and was made in Switzerland.
The Internet was invented on 1968-1970. (Wasn't known as the internet at that point). The Internet is the infrastructure.