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hyperlink
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link
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Google Adwords
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advertising through Google
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NNPA
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National Publishers Association (was the National Negroes Publishers Association)...more than 200 black newspapers aee part of it
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hate mail
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harassing and/or threatening electronic mail
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Five W's
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Who, What, When, Where, Why
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HTML
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protocal that controls how web pagesare formatted and displayed
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microprocessors
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miniature circuits that process and store electronic signals, integrating thousands of electronic components into thin strands of silicon along which binary codes travel
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flame
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a mean or hurtful e-mail message
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code
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written instructions in a computing language
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Web site
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A collection of related web pages
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e-mail
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electronic mail messages sent over the internet; developed by computer engineer Ray Tomlinson in 1971
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wiki
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website that allows easy creation and many authors WYSIWYG ( what you see is what you get)
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Define amplitude modulation.
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Amplitude modulation varies the amplitude of a carrier in proportion to the information being sent. The carrier goes on ocillating at a fixed requency but the amplitude of the wave varies. ONLY the amplitude of the sine wave is mdified.
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ascii
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a standard code, consisting of 128 7-bit combinations, for characters stored in a computer or to be transmitted between computers.
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antivirus
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software that helps protect a computer from malicious code
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Convergence
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The merging of two or more different technologies
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Recent E-commerce Development
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user status - credit card theftAnytime-anywherecredit card security - if people do not believe that transactions are safe they will not buy as muchonline advertisement
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Define frequency.
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The number of ocillations per unit time (usually seconds).
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How do you calculate the decibel value of a power difference?
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dB=10log10(P2/P1)
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cringe
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to shrink, bend, or crouch, esp. in fear or servility; cower.
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cyber grooming
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Enter your back text here.the process that online predators use to trick their victims by building false trust
and relationships
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hacker
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a person who uses the Internet to break into a computer or computer network
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home page
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first page that is displayed when the browser is launched
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privacy policy
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describes how a company or group will treat personal information when you use their products/ services
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Define frequency modulation.
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The amplitude of the carrier remains fixed, but the frequency changes according to the signal. When the signal is stronger, the carrier frequency is increased.
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Describe data representation.
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Syntax of data items that are exchanged, specific form used during transfer, translation of integers, characters, and files between computers.
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What is packet switching?
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Packet switching divides data into small blocks called packets and includes the recipient's id.
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WTF is Internetworking?
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A set of standards to interconnect many packet switching technologies, ultimately it would become TCP/IP.
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malicious code
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a computer program that is meant to hurt you and your computer ( viruses, worms,
and Trojan horses)
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Describe simplex mode.
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It's a channel where the data only goes in one direction. Broadcast radio or TV is like this.
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What are the characteristics of FTP?
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Arbitrary file contents, bidirectional transfer, support for authentication and ownership, ability to browse folders, textrual control messages, accomodates heterogeneity.
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What is a communication protocol?
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A communication protocol specifies the details for one aspect of a computer communication, including actions to be taken when errors or unexpected situations arise. A given protocol may specify details such as voltage and signals or high level things suc
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What are the characteristics of HTML?
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Uses text representation, describes pages containing multimedia, is declarative instead of procedural, provides markup specs not formatting, permits a hyperlink to be embedded in an arbitrary object and allows a document to include metadata.
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What does UDP stand for?
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Unreliable Damn Protocol. (User datagram protocol)
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HTML (HyperText Markup Language)
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The language of the World Wide Web used to create Web pages, with hyperlinks and markup for text formatting (heading styles, bold, italic, numbered lists, insertion of images, etc.)
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Why are sine waves even important?
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Because many natural phenomena produce a signal tha corresponds to a sine wave as a function of time.
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What /is/ Shannon's theorem, then?
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Channel capacity limit = (Bandwidth in hz) log2 (1+S/N) Where S/N is the signal to noise ratio, or P2/P1, NOT the raw dB value.
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Compare optical fiber versus copper.
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Optical fiber: Immune to electrical noise, less signal attenuation, higher bandwidth. Copper wire: lower cost, less expertise/equipment needed, harder to break.
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What are the characteristics of the Message Paradigm?
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Connectionless, many to many communication, sequence of individual messages, each message limited to 64K, used for multimedia, build on UDP
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What does a codec do?
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A codec converts analog signals into digital signals.
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What are the characteristics of HTTP?
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Uses text control messages, transfers binary data files, can download or upload data, incorporates caching
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What is a concurrent server?
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A concurrent server uses threads of execution to handle requests from multiple clients at the same time.
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What does a client side socket call look like?
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socket, connect, send/receive, close
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What's interesting about digital bandwidth?
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Fourier analysis of a digital signal produces an infinite set of sine waves that grow to infinity. In short: A digital signal has infinite bandwidth.
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What are the three main sources of transmission errors?
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Interference (Background EMF, cosmic rays), Distortion (all physical systems distort signal), Attenuation (signal becomes weaker as it travels distances through a medium and radio becomes weaker over distance)
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Describe full duplex transmission.
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Both sends and receives. So, like a voice conversation over the phone.
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What is manchester encoding?
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It's a standard for line coding. It's used with Ethernet. It uses transition, rather than levels, to define bits. A 1 corresponds to a transition from 0 to positive. A zero corresponds to a transition from positive to 0.
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What's important about differential manchester encoding?
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It works even when two wires are reversed.
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What is the ISO layering model?
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Like TCP/IP except the top three layers = level 5 of TCP/IP.
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What is a low pass filter?
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A low-pass filter is a filter that passes low-frequency signals but attenuates (reduces the amplitude of) signals with frequencies higher than the cutoff frequency. The actual amount of attenuation for each frequency varies from filter to filter.
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Really? WTF is Quadrature Amplitude Modulation?
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We combine phase key shifting with amplitude modulation. So you have a constellation diagram like before, but now with layers like an onion.
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What does a constellation diagram show?
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The assignment of data bits to phase changes.
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What steps does the server take to talk to a client?
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Starts before the client, registers services on its ports with the local system, waits for a client to contact it, interacts with client, waits for next client.
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What time elapses between samples for the PCM encoding used in the telephone system?
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The telephone system samples at 64k bits per second, so the time elapsed between samples is .000016 seconds, roughly.
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What is phase shift modulation?
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You can vary the phase of a wave according to signal changes, but we don't usually do this because if phase changes after a cycle k, the next sine wave will lag and so a slight delay resembles a change in frequency, so in analog it's really a special case of frequency modulation.
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What is a private network?
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A network is private if use of the network is restricted to one group. (May include circuits leased from a provider.)
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Describe how the focus of the internet has shifted.
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The availability of high speed computation and communication tech shifted the focus of the internet from resource sharing to general purpose communication.
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What are the five key aspects of networking?
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network apps and programming, data communications, packet switching and net tech, internetworking with tcp/ip, and additional networking concepts and technologies
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So, you're using CRC. What do the sender and receiver have to do?
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They use ARQ (automatic repeat request) so that if the sender doesn't get an acknowledgement back from the receiver, it automatically sends it again. If a transmission error occurs, the receiver just discards the message and waits for the sender to resend.
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Describe the internet layer of TCP/IP (layer 3)
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These protocols form the basis for the internet. They include the internet addressing structure, the format of internet packets, the method for dividing a large packet into smaller ones, and error reporting.
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Again, how exactly does differential manchester encoding work?
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A '1' bit is indicated by making the first half of the signal equal to the last half of the previous bit's signal i.e. no transition at the start of the bit-time. A '0' bit is indicated by making the first half of the signal opposite to the last half of the previous bit's signal i.e. a zero bit is indicated by a transition at the beginning of the bit-time. In the middle of the bit-time there is always a transition, whether from high to low, or low to high. A reversed scheme is possible, and no advantage is given by using either scheme.
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What are the characteristics of a client application?
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Starts after the server app, must know what server to contact, initiates contact whenever communication is needed, communicates with server by sending and receiving data, may terminate after interacting with a server.
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An extention of Nyquist's theorem is Shannon's theorem. What does Shannon's theorem tell us?
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It is used to specify the maximum data rate that can be achieved over a transmission system that DOES have noise.
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How has sound data being sent across the internet evolved?
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alert sounds to human voice to audio clips to high fidelity audio.
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What are the media that go with light energy?
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Optical fiber, IR, Laser. That's right, frickin' laser beams.
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What is the overall purpose of the DNS system?
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The Domain Name System provides a service that maps human readable symbolic names to numeric computer addresses.
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What's the problem with Single Parity Checking?
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It's very weak. If you flip an even number of bits in error, single parity checking won't catch it.
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What is the lifetime of a socket in a concurrent server?
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The original socket used to accept connections exists so long as the main server thread executes. a socket used for a specific connection exists only so long as the thread exists to handle that connection.
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How does Single Parity Checking work?
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A bit is added to one end or the other of a piece of information, indicating odd and even parity. The communication protocol has to be set up for this. In even parity checking, it counts the number of ones in a piece of information. If that number is even, the parity bit is 0. If odd, then 1. (Zero ones are even) So if the count of the data bits received don't check out with the parity bit, some kind of error handling happens.
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How do you find the CRC, given a data word and a generator?
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take the dataword, add as many zeroes as the CRC is long, and xor "divide" the generator into it. The CRC will be the remainder.
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If the maximum frequency audible to a human ear is 20kHz, at what rate must the analog signal from a mic be sampled in converting to digital?
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sampling rate= 2 * fmax. Our fmax is 20khz. 2*20k=40k. So sample 40,000 times per second.
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How many signal levels does it take to send n bits?
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2^n. Two signal levels can only send one bit at a time, four signal levels could send two bits at a time.
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LAN
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local area network
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1999
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Shawn Fanning invents Napster
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lan LAN
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local area network
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PPT
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PowerPoint presentation software: an electronic slideshow
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Spam
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Unsolicited bulk email; online "junk" mail
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Advanced Form
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experimental (the original developers of the internet did not become rich because they worked for the governmentelite (early areas that used computers for specific things)mass communications
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download
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to transfer (software, data, character sets, etc.) from a distant to a nearby computer, from a larger to a smaller computer, or from a computer to a peripheral device.
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ISP
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Internet Service Provider: a vendor that provides Internet access to its customers
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Cold War Aug 1957
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USSR test fires ICBM
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host computer
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computer that is accessed remotely from a user's computer
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philshing
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an internet scam that begins with phone e-mail messages that appear to be from an official site and request that customers send their credit card numbers and other personal information to update the account
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What is Nyquist's theorem?
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sampling rate=2 * fmax
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considered
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To think carefully about, esp. in order to make a decision; contemplate; reflect on:
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IP
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Implementation Plan: a form that must be completed and submitted to i-SAFE to
notify us of an event, generate an ID number, and facilitate a store order for materials
necessary for an event
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URL
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Uniform Resource Locator; a URL is a web address for a web site
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Telecommunications Act of 1996
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the sweeping update of telecommunications law that led to a wave of media consolidation
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world wide web
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a system of extensively interlinked hypertext documents: a branch of the Internet.
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bulletin boards
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message boards: public areas on the Internet where messages or comments can be posted for other board members to read and reply to
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google model
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1. Make it Free
2. Attract a user base
3. Figure out how to make $ with the user base
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The first internet election
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youtube presidential debates made 2008 the first Internet election...candidates made more extensive use of the internet than any other time in history...Obama announced Biden as VP over Twitter
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What's differential manchester encoding?
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Like manchester encoding, but relies on relative transitions, rather than absolute ones.
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What are the two mail access protocols?
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POP and IMAP.
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What's cool about CRC?
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It allows for arbitrary message length, since it's bit order dependent it is good at finding errors, and it's very fast to do at the hardware level.
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chat room
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a virtual room or gathering place for Internet users who have shared interests to
congregate and converse
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What does a transmitter do?
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A transmitter encodes digital data into digital signals using manchester, differential manchester, or other line coding.
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Define wavelength.
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The length of a cycle as a signal propagates across a medium.
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So if phase key shifting is limited, what else can we do to increase the data rate?
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Quadrature amplitude modulation.
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A communications channel is classified as one of three types. What are those types?
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Simplex, Full duplex, and Half duplex.
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What are the physical media that go with electrical energy?
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Twisted pair and coax.
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What is a URL? (Uniform Resource Locator)
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A representation standard that specifies the format and meaning of web page identifiers.
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What does the HTTP request HEAD do?
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Requests status information, server responds by sending status info, but NOT a copy of the doc.
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What are the characteristics of SMTP?
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Stream paradigm, uses textual control messages, only transfers text messages, allows a sender to specify recipeints, sends one copy of a given message.
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What are the properties of the Stream Paradigm?
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Connection oriented, 1-1 communication, sequence of individual bytes, arbitrary length transfer, used by most apps, build on TCP
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What are the media that go with electromagnetic (radio) energy?
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Terrestrial radio and satellite.
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What is Pulse Code Modulation?
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A technique where the level of an analog signal is measured repeatedly at fixed time intervals and converted to digital form.
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What are the five layers of TCP/IP?
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Layer 5: Application; Layer 4: Transport; Layer 3: Internet; Layer 2: Network Interface; Layer 1: Physical
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What does a telephone do, signal-wise?
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It converts analog data into analog signals.
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What are the two important email representation standards?
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RFC2822 Mail Message Format and Multi-purpose internal mail extensions (MIME).
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What does a server side socket call look like?
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socket, bind, listen, accept, send/receive, close.
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What are the three types of satellites?
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Low Earth Orbit, Medium Earth Orbit, and Geostationary Earth Oribit
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Where does the information come from in data communications?
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It can be arbitrary and includes devices other than computers.
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What is a public network?
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A public network is owned by an ISP and offers services to subscribers.
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How does socket inheritance work in multithreading?
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Each new thread that is crated inherits a copy of all open sockets from the thread that created it.
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What are the conceptual pieces of a data communications system?
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Preparing information from the source to transmit, transmitting across a physical medium, extracting information from the source and delivering it.
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What is a composite signal?
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It's a signal that can be broken down into simple waves.
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What does the http request PUT do?
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Sends data to a server, the server uses the data to completely replace the specified item (ie, overwrites the previous data)
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When does the transition occur in manchester encoding?
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In the middle of the time slot allocated to a bit. This allows the signal to return to the previous level in case the data contains two repeated 0s or 1s.
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How does a client identify a server?
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By an identifier for the computer on which a server runs (IP) and the port.
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What is the advantage of phase shift keying?
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The ability to represent more than one data bit at a given change.
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Most of the socket functions are self explanatory, but what is bind?
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Bind will bind a socket to a port number so that a service can run on it.
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How long does a signal take to travel from ground to a GEO satellite and back?
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Well, it's 35,785 km to a geostationary satellite from earth, so there and back is two times that. The signal travels at the speed of light, which is 3*10^8 meters per second. So (2 * (35.8*10^6))/(3*10^8) = .238 seconds.
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What is the chief advantage of a Differential Manchester Encoding?
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(in this case 0 is a transition and 1 is no transition) The advantage to this is that it works even if the two wires carrying the signal are reversed, since it's relative not absolute.
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What does Nyquist's theorem do in this case?
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It tells us that there is a bound on the maximum rate at which data can be sent without considering the effect of noise.
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What about row and column parity? How does it work?
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When you add up the parity both down and across, you can zero in on the problematic bit, which can be corrected if there's only one of them. This will also catch errors in which two or three bits have changed, even if it can't correct them, opening the way to ask for re-sending.
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