Term
| Why computers alone are useful? |
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Definition
- Connected computers are useful. For Example: In mid 1990 when the internet, along available to reseachs,became generally available to the public
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Term
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- The interne is the totaliy of all wires, fibers, switches, routers, satelite links, and other hardware for transportting information between addressed computers.
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Term
| What is the use of internet? |
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Definition
- It is conveniently and inexpensively to connect computer to the internet
- thereby connect to all other computers attached to the internet
- send emial and surf the web from home
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Term
| What is the two entities of communcation? |
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Definition
- people or computers which can be seprated into two broad classes synchronous and asynchronous
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Term
| Synchronomous Communcation |
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Definition
- requires that both the sender and the receiver ae active at the same time
( telephone conversation can be one example)
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| Asynchronous Communcation |
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Definition
- The sender and receiving occur at different times ( Postcard and Text Message are one example)
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- involves a single sender and many receivers ( Radio and Television are one example)
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- Used when there are many receivers, but the intedned recipients are not the whole population ( Magazine is one example)
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Term
| What is the opposite of broadcasting and multicasting? |
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Definition
- Point to point communcation
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Term
| Point to point communcation |
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Definition
- Telephone communcation and text message are point to point because there is one specific sender and one specific reciever
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Term
| The Internet's Comuncation Properites |
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Definition
- The internet support point to point asynchronous communcation
- The fundamental feature of the internet is provide a general communcation fabric linking all computer connected to it
- For Example the internet act like postal system but at electroinc speed
- Infact the internet can mimic synchronous communcation because of the we can chat
- Multicasting is possible
- It possible to post web page or youtube
- The internet offer a form of broadcasting that compare with radio or televsion
- The internet is truly a universal communcation medium
- The internet become more effective with each addition computer added to it
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Term
| The Client/Server Structure |
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Definition
- Most interaction over the internet use a protocal client/server structure
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Term
| Many Berief Relationships |
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Definition
- Webserver can hundle many clients at a time
- Client can be served by many webserver
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Term
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Definition
- The most basic level the internet is a point to point asynchronomous comuncation system and software has been built on it to implement on it to implement the many form of communcation we use
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Term
| The name game of computer addresses |
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Definition
- The internet uses pont to point communcation
- whe anything is send to point to point such as phone converstion the destination address is required
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Term
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Definition
- Each computer connected to the internet is given a unique address
- IP addresses is a series of four number (one byte each) separated by dots
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- Is a related group of network computers
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Definition
- Translates the hierarchical human readable names into the four number IP addresses which allowes both people and computers to use thier preferred naming
- Computer that connected the internet know the IP address of it nearest (DNS) name server
- Computer keeps list of human readerable symbolic name and the corresponding IP addresses
- whenever you use the heirarchical sysbolic name to send infrmation to some destination your computer ask the DNS server to look up the crossponding IP adress
- Then use the IP address to send the information
- when computer ask a DNS name servcer to translate a name to the IP address it is another client/server relationship
- usually the DNS server knows the translation for the symbolic name to the ip address because it has processed the IP adress befroe, save it. therefore replyes immediately
- But if does not know for the IP adress it looks for it by asking an authoritative name server
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Term
| Authoritative name server |
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Definition
- the name server keeps the complete list of the IP address and corresponding dommain for all authoritative name servers and computers in its domain. ( it's the got to name)
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Term
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Definition
- The edu domain for educational institution is one of serveral top level domain nams, often abbriated TLDs.
- .com for coomercail enterprises
- .org for organizations
- .net for nerwork
- .mil for the military
- .gov for the government agencies
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Term
| Transmission Control Protocol/Internet Protocol |
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Definition
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Definition
- It like postcard has space for one unite if information, destantion, IP address and sequnce number
- the packet are sent over the internet one at a time using whatever route available
- at the destantion they are reordered by the sequence number to assamble the information
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Term
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Definition
- It is natural to assume that the IP packet would take a single path to thier destination like conventional telephone calls, but they do not
- Because each packet can take a different route, congestion and service interruptions do not delay transmission
- The TCP/IP packets is independent
- TCP/IP protocol is robbust, meaning that it continues to work under adverse condition condition
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Term
| Moving Packets: Wires and More |
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Definition
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Term
| Far and Near: Wan and Lan |
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Definition
- The internet is a collection of wide area networks ( WAN)
- The internet is a collection of point to point channls and packets must visit a sequence of computer to reach thier destination
- In network term packet take several hops to be delivered
- Ethernet os the main technology for local area networks and is appropraite for connecting a;; the computers in a lab or builing
- The internet and ethernet are radically different
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Definition
- Networks designed to send information between two location widely separated and not directly connected
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Definition
- When the computer are close enough to be linked by single cable or pair of wires, the interconnection
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Definition
- Robert metcalfe is the inventor of the ethernet
- Enginners"tap" the channel to connect a computer allowing it to send a signal
- Then drive an electronic pulse or light flash onto the channel
- All computer connect to the channel can detect the signal, including the sender and channel support broadcast communcation
- Ethernet communication work like the party protocol for instance
- when someone telling the stroy the computer listen to the stroy
- only one computer typically keeps the transmited information and the broadcast meddium is being used for point to point communcation
- pause indicate the end of the transmission when no computer is sending signals and channel is quiet
- Computer wanting to transmit starts sending signals and at the same time start listening to the channel to detect what is being tranmited
- If it is exactly the information the computer sent the computer knows its the only one sending and it complete its tranmission
- If the computer signal are mixed in with signal from one or more other computers it notices the garbled message and stops transmitting immediately
- the other computer stop to and each machine puase for random length of time
- the computer that waits tge sortest length of time begins sending and if there are one conflecting computer it contnues. if not the colliders repeat the process
- Etherbet scheme is completely decentralize and requires mo schedule or plan
- Each computer listens to the channel and if it quiet it free
- The computer transmits unless some other computer start at the same moment then both computer back off for a brief random amount of time and then try again
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Term
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Definition
- Depedning on the technology the phyiscal setup for an etherent network is a wire, wire pair or optical fiber
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Term
| Connecting a Computer to the Internet |
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Definition
- When someone wan to connec to the internet it is just there
- Conection via an Internet service provide (ISP)
- Connection provider by a computer or enterprise network
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Term
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Definition
- Internet service providers sell connection to the internet for exaple phone
or cable compnay
- The ISP compnay places a modem at your house
- modems convert the bits a computer output into a form ( orange line) that is campatible with the carrier
- These signal are sent to the carrier business where they are convering ( via another modem) into a form suitable for the server that connect to the internet via the internet gateway .
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