Homework 1
2. Do any of these organizations provide free access to standards? If so, which ones?
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Yes, two of them provide free access to standards to some degree. For IETF’s (Internet
Engineering Task Force) standards called RFCs (Requests for Comments) are all freely
accessible. ITU’s (International Telecommunication Union) standards called
“Recommendations” are mostly free to access, mainly ITU-T and ITU-R. As for ISO
(International Organization for Standardization), it is an independent body, and protected
by copyright so it needs to be purchased.
4. What are the seven layers of the OSI model and, in general, what are the tasks that each is
responsible for?
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Physical Layer: Transmit raw bits through the physical medium (cables, radio waves…)
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Data Link Layer: Ensure that there is no error when data is transferred between two
devices.
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Network Layer: Decides the physical path which the network will take.
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Transport Layer: Provide end-to-end communication between applications on different
hosts.
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Session Layer: Manage sessions between applications on different hosts.
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Presentation Layer: Ensure that the data is in a usable format for the application.
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Application Layer: Provides network services directly to end users and applications.
6. Define the following concepts using complete sentences.
6a. A source is a system that generates and sends the original data to be transmitted through a
communication channel.
6c. A transmitter is a hardware that converts data into an electromagnetic signal (radio waves,
electric, light) and sends it over a communication medium.
6g. A bit is the smallest unit of digital information that represents a single binary value of 1 or 0.
6i. A protocol is a set of rules that define how data is formatted, transmitted, and interpreted
between devices on a network.
6k. Open System Interconnection model or OSI model is a conceptual framework with seven
layers that standardize how different computer systems communicate and exchange information
over a network.
8. What do you hope to gain by studying data communication theory?
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I just want to understand how data is transmitted between devices, such as through radio
waves, and whether another device on the same wavelength can intercept that
information. I’m also interested in how communication systems protect against this type
of interception.
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