Chapter 6

imissyou419's version from 2017-03-04 16:06

Section 1

Question Answer
PSTNtied to cellphone networks (public switched telephone network)
Financial networksABM & credit card transactions
LANHandles electronic key access in hotel (local area network)
Wireless networkoperates over LAN, provides internet access
WANprovides internet access for email and web browsing (wide area network)
Cell phone networktext message & multimedia messaging devices
GPSSatellite network service

Section 2

Question Answer
Collaborationwhen 2 or more people work together to achieve a common goal, result, or product; when effective, results of group are greater than those of individual work
Effectiveness of collaborative efforts driven by 4 factors:1. communication skills and culture (ability to be part of a group and give & receive critical feedback, members need to be able to openly share idea and criticize each other),
2. communication systems (availability of email, virtual private networks, IM, video conferences; depends on an organization's network technology) , 3. content management (keeping track, synchronizing, integrating versions to ensure conflicts don't occur),
4. workflow control (a process or procedure by which content is created, edited, used, and discarded; business process focuses on external delivering a product or service to a customer while workflow focuses on internal delivery of a good or source i.e. 1 person create webpage, 1 person review webpage)
Workflowa process or procedure by which content is created, edited, used, and discarded; workflow focuses on INTERNAL delivery of a good or service
LANcomputers are connected AT A SINGLE PHYSICAL SITE;
within a small & single geographical location;
number of connections range from 2 - several thousand
WANconnect devices at different geographical locations
Internet and internetsNetwork of networks;
The Internet: collection of networks that you use when you send email or access a website;
Intranets: private newtork of networks
Protocola set of rules that communicating devices follow
Layered protocolwhen an elaborate scheme is used to provide seamless flow
Switchspecial purpose computer that receives and transmits messages on the LAN
Network interface card (NIC)a hardware component that each device on LAN has; connects the device's circuitry to the network cable;
works with programs in each device to implement the protocol necessary for communication;
newer machines have integrated NIC - a NIC that is built into the computer
MAC (media access control) addressalso called physical address; a permanent address given to each NIC at the factory; address enables device to access network,
Unique identifier
Unshielded twisted pair (UTP) cablea type of cable used to connect computers, printers, switches, and other devices on LAN;
has 4 pairs of twisted wires;
a device called RJ-45 connector used to connect UTP cable to NIC devices
Optic fiber cablesa type of cable used to connect computers, printers, switches, and other devices on LAN;
signals on cable are light rays and reflect inside glass core of optic fiber cable;
Advantages over UTP: resistance to signal interference, greater transmission distance so ideal for undersea cables, more secure b/c use optic pulses instead of electrical signals, wrapped in protective covers and use special connectors) but fragile
IEEE 802.3 protocolcalled Ethernet, specifies how messages are to be packaged and processed for transmission over the LAN; used on WAN & LAN
onboard NICa built-in NIC, in most PC that supplies 10/100/1000 Ethernet
Wireless NIC (WNIC)device that enables wireless networks by communicating with wireless access points; can be cards that slide into PCMA slot or built-in onboard devices; operate according to 802.11 protocol or Wireless LAN or WiFi
Access points (AP)points in a wireless network that facilitate communication among wireless devices;
serve as points of interconnection b/w wireless and wired networks; must be able to process messages according to 802.3 and 802.11 protocols because they send and receive wireless traffic using 802.11 and communicate with wired network using 802.3
Repeaters and reflectorsused to amplify and reflect signals to extend the range
M-commerce (mobile commerce)its application allows mobile phones to conduct certain kinds of transactions i.e. mobile banking
Bring your own device (BYOD)An approach that many organizations are adopting where employees are encouraged to use their own device for work instead of being provided with additional company-issued devices
Routerimportant component of WAN; special-purpose devices that implement the protocol for WAN; router normally connect your computer to ISP owned computers
ISP 4 functions1. provides computer/router with an internet address,
2. serves as your gateway to the internet,
3. passes communications back and forth between user and internet,
4. pay for the internet (collect money from customers and pay access fee on your behalf)
Hypertext transfer protocol (HTTP)subset of the internet and consists of sites and users
Browserprogram that access HTTP protocol; receives, displays, processes HTML docs; transmits responses
Uniform resource location (URL)address on the internet stated in a way humans can remember (not the actual address on the network)
Public IP addressused on the internet; assigned to ISPs and major institution in block by ICANN; each unique across all computers on the internet
Logical addressIP address is assigned through a software and not a physical address such as MAC on a NIC
Private IP addressused within private networks and internets; controlled by organization that operates the private network or interest
Domain name system (DNS)a system that converts user-friendly names into their IP addresses; any registered, valid name
Domain name resolutionsthe process of converting a domain name into a public IP address
Domain name resolverscomputers that do the domain name resolution;
reside at ISP, academic institutions, large companies, gov organizations; keep track of domain name req, store locations for future use; when a resolver can't find a domain name, it will search for IP address at a resolver that is at a higher level in the network => takes time for low-level resolvers to acquire info


Question Answer
Analoga continuously variable electronic signal
Modulator/demodulator or Modemconverts the computer's digital data into analog signals that can be transmitted over the telephone line (DSL line) or cable line
Digital subscriber line (DSL) modemoperates on the same line as voice telephone but doesn't interfere with it; always maintain a connection - no need to dial in
Asymmetric digital subscriber line (ADSL)has different uploads and speeds; used in most homes and businesses;
receive more data than they transmit and don't need to transmit as fast as they receive data
Symmetric digital subscriber line (SBSL)offers the same fast speed in both directions; 5 Mb/s
Cable modemtype of modem that provides high speed data transmission using cable television lines;
cable company install a fast, high-capacity optic fiber cable to a distribution centre in each neighborhood that it serves; at the distribution centre, the optic fiber cable connect to regular TV cables that run to its subscriber's home or business;
cable modems modulate in a way that their signals don't interfere with TV signals - always on
What is better? digital or analogdigital because they are reproduced exactly with no distortion or loss while analog signals must be amplified which introduces noise and distrotion
Wireless Wan (WWAN) vs. wireless LAN1. WWAN covers a larger area than wireless LAN
2. WWAN uses cellular networks to transfer data
Application layerLayer 4
Data is passed between programs (email app, browser, file transfer program) and transport layer
Transport layerLayer 3
Deals with opening connections & maintaining them
Uses TCP
Which works to ensure packets are received with correct connect
Internet LayerLayer 2
Works with IP addresses
Many ways to navigate packets from 1 IP to another
Control packet organization and timing contraints
Network access layerLayer 1
Describes the equipment that is used for communications (UTP, fiber-optic), signalling use (analog, digital), and protocols used to communicate between machines
Transmissions within a single network (LAN)
Transmission control program/ internet protocol (TCP/IP)(how data is transmitted across the internet)
1. getting internet access and pressing "send/receive",
2. breaking apart messages into pieces called segments and get ready for transport - job of TCP,
3. send & receive packets - TCP interact with IP protocol (IP packages segments into packets) (layer 2),
4. reassemble packets at correct router destination and display message - TCP unpackages it
FirewallComputer device that prevents unauthorized network access
Can be a special-purpose computer or a program on a general-purpose computer or router
PortA number that is used to uniquely identify a transaction over a network
The port number specifies the service provided
Access control list (ACL)Component of firewall
Keeps track of which IP addresses are allowed access and which are prohibited
Packet-filtering firewallsSimplest type of firewall
Examines each part of message and determines whether it should let that pass by examining the source address, the destination address, and other data
Can prohibit outsides from starting a session with any user behind the firewall
Can disallow traffic from particular sites and prohibit traffic from legit but unwanted addresses
Keep employees from using specific sites
Help protect computers from unauthorized network access
EncryptionProcess of transforming clear text into coded, unintelligable text for secure storage or communication
The encryption algorithm applies the key to original msg to produce coded message; key applies key to coded message to recover original msg
Symmetric encryptionSame key used to encode and decode
Asymmetric encryptionDifferent keys used
HTTPsA protocol used for the most secure communication over the internet
- Data encrypted using a protocol called Secure Socket Layer (SSL) aka Transport Layer Security (TLS)
- uses a combination of public/private key and symmetric encryption
1. your computer obtains public key for website to which it will connect
2. your computer generates a key for symmetric encryption
3. your computer encodes key using website's public key - sends enrypted symmetric key to website
4. website encodes symmetric key using its private key
5. computer and website communicate using symmetric encryption
Virtual private network (VPN)communication alternative
uses the internet or private internet to create private point-to-point connections
offers the benefit of point-to-point leased lines & enable secure remote access
Tunnelvirtual, private pathway over a public or shared network from VPN client to VPN server
Web crawler (spider)software programs that browse the web in a methodical way
starts with list of seed URLs, visits the URLs and identify hyperlinks in the page
harvest specific things that can be used for spam (such as email)
2 considerations in search engines1. breadth of coverage - % web covered by search engines, 2. ordering of results from search