Summary
■ Digital encoding is the conversion of data into a digital pattern acceptable to
the network media.
■ A digital signal that fluctuates between a positive voltage level and zero-volt
level is called a unipolar digital signal.
■ A digital signal that fluctuates between a positive voltage level and a negative
voltage level is called a bipolar digital signal.
■ Manchester encoding is a common digital-encoding scheme used on LANs.
It is characterized by the digital pulse transitioning during the midpoint of
the timing period.
■ A digital signal that fluctuates between a positive voltage level and a negative
voltage level and never returns to zero for any measurable period of time is
known as non-return to zero (NRZ).
■ A synchronous signal is synchronized with a reference signal to ensure
proper timing.
■ An asynchronous signal is not synchronized with a reference signal and
typically uses a binary pattern to determine the stop and start of the signal.
■ A parity check is used to check the integrity of data.
■ A Cyclic Redundancy Check (CRC) is an enhanced parity check that not only
identifies when an error occurs but also corrects the error.
■ Data encapsulation is the process of surrounding the raw data with other
information needed for delivery.
■ The terms segment, frame, datagram, and protocol data unit (PDU) are used to
describe blocks of data.
■ The term protocol data unit (PDU) is the most technically correct term used to
describe data packaging.
■ A connection-oriented protocol establishes a connection with the destination,
transfers the data, and then releases the connection after all communication
has ended.
■ A connectionless protocol simply sends data to the destination.
■ A circuit-switching network establishes a physical connection between two
points.
■ A packet-switching network establishes a logical connection and may
use many different, physical paths to send data from the source to the
destination.
■ ASCII, EBCDIC, and UNICODE are coding standards, or data codes, that
represent the written word.
■ Binary Coded Decimal (BCD) is a coding standard that uses a four-digit
binary code to represent a number.
■ Various protocols are designed to package data in particular ways.
■ The OSI model is composed of seven layers, which explain the process of
encapsulating data for communication between two points on a network
system.
Review Questions
Answer the following questions on a separate sheet of paper. Please do not write in this book.
1. When does digital encoding take place?
2. Describe the Manchester digital encoding scheme and how it is related to
binary signals.
3. The type of transmission in which the digital signal is synchronized with a
reference signal to ensure proper timing is called _____ transmission.
4. The type of transmission in which no reference signal is present is called
_____ transmission.
5. What is a parity check?
6. What is a Cyclic Redundancy Check (CRC)?
7. Describe the complete data packaging process, from raw data (text file,
sound, or graphic) to digital signals.
8. A(n) _____ protocol first establishes a connection with the destination
computer before transmitting data.
9. A(n) _____ protocol sends data to a destination computer without first
establishing a connection.
10. What is the difference between packet switching and circuit switching?
11. Name three encoding standards used to represent written language as binary
numbers.
12. What does the acronym ASCII represent?
13. Which standard was designed to represent plain text files?
14. What code is used to represent strictly numerical data?
15. What code format does IBM mainframe computers use?
16. What code can be used to represent over 65,000 different characters?
17. Draw and label a UDP frame.
18. Compare and contrast an Ethernet II frame with an IEEE 802.3 frame.
19. What layer of the OSI model is responsible for the conversion of different
coding formats?
20. What layer of the OSI model routes data packages based on the IP address?
21. What layer of the OSI model is concerned with the media, hardware, and
topology of the network?
22. What OSI layer is responsible for converting data into digital signals?
23. What OSI layer converts data into a form acceptable to both the source and
destination?
24. What OSI layer is concerned with encrypting data?
25. What OSI layer is concerned with establishing and ending the connection to
the destination?
26. What OSI layer negotiates the connection between the destination and
source?
27. What OSI layer decides if TCP or UDP is to be used as the protocol for
transmitting the data?
■ Digital encoding is the conversion of data into a digital pattern acceptable to
the network media.
■ A digital signal that fluctuates between a positive voltage level and zero-volt
level is called a unipolar digital signal.
■ A digital signal that fluctuates between a positive voltage level and a negative
voltage level is called a bipolar digital signal.
■ Manchester encoding is a common digital-encoding scheme used on LANs.
It is characterized by the digital pulse transitioning during the midpoint of
the timing period.
■ A digital signal that fluctuates between a positive voltage level and a negative
voltage level and never returns to zero for any measurable period of time is
known as non-return to zero (NRZ).
■ A synchronous signal is synchronized with a reference signal to ensure
proper timing.
■ An asynchronous signal is not synchronized with a reference signal and
typically uses a binary pattern to determine the stop and start of the signal.
■ A parity check is used to check the integrity of data.
■ A Cyclic Redundancy Check (CRC) is an enhanced parity check that not only
identifies when an error occurs but also corrects the error.
■ Data encapsulation is the process of surrounding the raw data with other
information needed for delivery.
■ The terms segment, frame, datagram, and protocol data unit (PDU) are used to
describe blocks of data.
■ The term protocol data unit (PDU) is the most technically correct term used to
describe data packaging.
■ A connection-oriented protocol establishes a connection with the destination,
transfers the data, and then releases the connection after all communication
has ended.
■ A connectionless protocol simply sends data to the destination.
■ A circuit-switching network establishes a physical connection between two
points.
■ A packet-switching network establishes a logical connection and may
use many different, physical paths to send data from the source to the
destination.
■ ASCII, EBCDIC, and UNICODE are coding standards, or data codes, that
represent the written word.
■ Binary Coded Decimal (BCD) is a coding standard that uses a four-digit
binary code to represent a number.
■ Various protocols are designed to package data in particular ways.
■ The OSI model is composed of seven layers, which explain the process of
encapsulating data for communication between two points on a network
system.
Review Questions
Answer the following questions on a separate sheet of paper. Please do not write in this book.
1. When does digital encoding take place?
2. Describe the Manchester digital encoding scheme and how it is related to
binary signals.
3. The type of transmission in which the digital signal is synchronized with a
reference signal to ensure proper timing is called _____ transmission.
4. The type of transmission in which no reference signal is present is called
_____ transmission.
5. What is a parity check?
6. What is a Cyclic Redundancy Check (CRC)?
7. Describe the complete data packaging process, from raw data (text file,
sound, or graphic) to digital signals.
8. A(n) _____ protocol first establishes a connection with the destination
computer before transmitting data.
9. A(n) _____ protocol sends data to a destination computer without first
establishing a connection.
10. What is the difference between packet switching and circuit switching?
11. Name three encoding standards used to represent written language as binary
numbers.
12. What does the acronym ASCII represent?
13. Which standard was designed to represent plain text files?
14. What code is used to represent strictly numerical data?
15. What code format does IBM mainframe computers use?
16. What code can be used to represent over 65,000 different characters?
17. Draw and label a UDP frame.
18. Compare and contrast an Ethernet II frame with an IEEE 802.3 frame.
19. What layer of the OSI model is responsible for the conversion of different
coding formats?
20. What layer of the OSI model routes data packages based on the IP address?
21. What layer of the OSI model is concerned with the media, hardware, and
topology of the network?
22. What OSI layer is responsible for converting data into digital signals?
23. What OSI layer converts data into a form acceptable to both the source and
destination?
24. What OSI layer is concerned with encrypting data?
25. What OSI layer is concerned with establishing and ending the connection to
the destination?
26. What OSI layer negotiates the connection between the destination and
source?
27. What OSI layer decides if TCP or UDP is to be used as the protocol for
transmitting the data?