Title: Module Two Quiz
Course: CNT 2001 Computer Networks & Communications > Section: Module 2 The OSI and TCP/IP Models

Q: At which OSI layer do POP3 and Telnet operate?
- Transport
- Session
- Presentation
- Application
A: Application
If right: The Application layer contains all the services and protocols, including POP3 and Telnet, needed by application software or the operating system to communicate on the network.

Q: Which standardization model describes the steps that data must go through to be transmitted across a data network?
- SOHO model
- UAC model
- Proprietary model
- OSI model
A: OSI model
If right: The Open Systems Interconnection (OSI) model was created by the International Standards Organization to describe the steps that data must go through in order to be transmitted across a data network. The OSI model was never intended to define how data moves across networks; instead, it was intended to describe how data is created and defined so that it could be sent over a network.

Q: What is the process of taking data from a higher layer of the OSI model and carrying it down into the next layer?
- embedment
- fixation
- encapsulation
- segmentation
A: encapsulation
If right: In networking, encapsulation is the process of taking data from a higher layer of the OSI model and carrying it down into the next layer. The reverse of this process is called deencapsulation.

Q: In what format is data sent at the Physical layer of the OSI model?
- bits
- segments
- packets
- frames
A: bits
If right: When the data frame reaches the bottom of the OSI model and enters the Physical layer, it is converted into bits, which are then passed down the network media to its destination computer.

Q: In what format is data sent at the Transport layer of the OSI model?
- bits
- segments
- packets
- frames
A: segments
If right: When data enters the Transport layer, it then becomes known as a segment.

Q: In what format is data sent at the Data-Link layer of the OSI model?
- bits
- segments
- packets
- frames
A: frames
If right: In the Data-Link layer, data packets are turned into frames.

Q: In what format is data sent at the Network layer of the OSI model?
- bits
- segments
- packets
- frames
A: packets
If right: As the segment is passed further down the OSI Model to the Networking layer, the segment becomes known as a packet.

Q: Which OSI layer is the lowest layer that sends data over a cable or wireless medium?
- Physical
- Data-Link
- Network
- Transport
A: Physical
If right: The Physical layer, as can be expected from its name, deals with all aspects of physically moving data from one computer to the next. The encapsulation units on this layer are called bits because this layer is concerned with converting data from the upper layers into 1s and 0s that can be transmitted over various types of transmission, called media.

Q: Which OSI layer is responsible for routing between networks?
- Physical
- Data-Link
- Network
- Transport
A: Network
If right: Whereas the Data-Link layer is responsible for moving data from one computer or node to another, the Network layer is responsible for routing data in the form of packets from one end of the network to the other.

Q: Which type of network communications protocol does not ask for verification that a data packet has successfully reached its destination?
- connectionless protocol
- connection-oriented protocol
- end-to-end protocol
- terminating protocol
A: connectionless protocol
If right: A connectionless protocol does not ask for verification that a data packet has successfully reached its destination. If a connectionless protocol is being used, the data packet is thrown out on the network and is just assumed that it successfully reached its destination. This best-effort delivery will usually suffice on most environments without problems.

Q: Which of the following is not a form of frame synchronization?
- time-based frame synchronization
- character counting
- byte stuffing
- clock threading
A: clock threading
If right: In frame synchronization, a specific frame type or protocol delineates to the computer the beginning and ending of any given frame. The four methods of frame synchronization are time-based frame synchronization, character counting, byte stuffing, and bit stuffing.

Q: At which OSI layer are logical addresses, such as IP addresses, defined?
- Physical
- Data-Link
- Network
- Transport
A: Network
If right: Logical addresses, such as IP addresses, need to be assigned manually to every computer on a network. These addresses are assigned at the Network layer.

Q: Which layer includes the MAC address?
- Physical
- Data-Link
- Network
- Transport
A: Data-Link
If right: The Data-Link layer is concerned with moving data (in frames) from one computer or node to another. In this layer, computers communicate by using a physical address called the MAC address.

Q: What method is used by a specific frame type or protocol to delineate to the computer the beginning and ending of any given frame?
- period counting
- signal threading
- frame synchronization
- clock threading
A: frame synchronization
If right: The Media Access Control sublayer determines where one frame ends and the next one starts. This method is known as frame synchronization.

Q: Which layer includes the cables, wireless cards, and hubs?
- Physical
- Data-Link
- Network
- Transport
A: Physical
If right: Because the Physical layer deals with all aspects of physically moving data from one computer to the next, it includes physical devices such as cables, wireless cards, and hubs.

Q: Which layer includes the Logical Link Control and Media Access Control sublayers?
- Physical
- Data-Link
- Network
- Transport
A: Data-Link
If right: The Data-Link layer is unique because it is divided into two sublayers to properly describe its full functionality. These two sublayers are called Logical Link Control (LLC) and Media Access Control. The LLC standard was created to facilitate communications between the upper Network Layer of the OSI Model and the Lower Physical Layer. The Media Access Control Sub Layer is used to determine which computer has access to the network media at any given time.

Q: Which OSI layer is responsible for managing the dialog between networked devices?
- Transport
- Session
- Presentation
- Application
A: Session
If right: The Session layer manages the dialog between networked devices. It can establish, manage, and terminate connections between local and remote computers or applications.

Q: Which communication method is a true two-way communication between devices?
- full-duplex
- half-duplex
- simplex
- half-simplex
A: full-duplex
If right: Duplex or full-duplex means true two-way communications between devices. Either end of the connection can transmit or receive at the same time the other end is doing the same thing.

Q: Which address ports range between 1,024 and 49,151?
- well-known ports
- registered ports
- dynamic ports
- recognized ports
A: registered ports
If right: Registered ports range from 1,024 through 49,151 and are registered with ICANN for specific uses, usually for a specific company, vendor, application, or operating system for proprietary use.

Q: Which address ports range from 49,152 through 65,535 and are available for any application to use to communicate with any other application?
- well-known ports
- registered ports
- dynamic ports
- recognized ports
A: dynamic ports
If right: Dynamic ports range from 49,152 through 65,535 and are available for any application to use to communicate with any other application. Dynamic ports are also sometimes known as private ports and ephemeral ports.

Q: A/An ___________ is a unique address inside the computer that is associated with a specific protocol, service, or application.
- IP address
- TCP address
- ICMP port
- port address
A: port address
If right: The Transport layer needs to ensure that the data it has sent can get to the proper destination applications, services, or protocols. To do this, the Transport layer uses port addressing. A port address is a unique address inside the computer that is associated with a specific protocol, service, or application.

Q: What port addresses range from 0 through 1,023?
- well-known ports
- registered ports
- dynamic ports
- recognized ports
A: well-known ports
If right: Port addresses especially apply to the TCP and UDP protocols and are divided into three categories or ranges: well-known ports, registered ports, and dynamic ports. Well-known ports range from 0 through 1,023 and are pre-assigned by the Internet Corporation for Assigned Names and Numbers (ICANN) for the use of major networking protocols. Well-known ports do not change, no matter what computer or operating system you use.

Q: TCP is an example of a ___________ protocol
- connectionless protocol
- connection-oriented protocol
- end-to-end protocol
- terminating protocol
A: connection-oriented protocol
If right: Connection-oriented protocols ask for verification that a packet has successfully reached its destination before sending another packet out. Most Network layer protocols used in modern networks, such as IP, are of the connectionless variety. However, TCP, one of the most widely used protocols at the Transport layer, is actually a connection-oriented protocol.

Q: Which OSI layer ensures that the data gets delivered safely to its destination?
- Transport
- Data-Link
- Network
- Physical
A: Transport
If right: Aside from breaking the data into segments or reassembling segments back into data, the Transport Layer is also concerned with the reliability of the transport of the data sent. What this means is that the one of the jobs of the Transport Layer is to ensure that the data that has been sent safely arrived at its destination.

Q: At which OSI layer do routers operate?
- Physical
- Data-Link
- Network
- Transport
A: Network
If right: The Network layer routes data in the form of packets from one end of the network to the other.

Q: At which OSI layer would a switch operate?
- Physical
- Data-Link
- Network
- Transport
A: Data-Link
If right: The Data-Link layer is concerned with moving data from one computer to another. Because switches forward traffic based on the MAC address, it operates at the Data-Link layer.

Q: At which OSI layer would a hub operate?
- Physical
- Data-Link
- Network
- Transport
A: Physical
If right: The Physical layer deals with all aspects of physically moving data from one computer to the next, including cables and hubs.

Q: Which layer of the TCP/IP model corresponds to the OSI Network layer?
- Application
- Transport
- Internet
- Network Access
A: Internet
If right: Whereas the OSI model is based on an idealized network environment and does not match any real protocol suites, the TCP/IP model is built around the TCP/IP protocol suite.

Q: Which layer of the OSI model discusses network services?
- Transport
- Session
- Presentation
- Application
A: Application
If right: The top layer of the OSI model is the Application layer, which contains all the services and protocols needed by application software or the operating system to communicate on the network.

Q: Which OSI layer includes SSL?
- Transport
- Session
- Presentation
- Application
A: Presentation
If right: The Presentation layer is concerned with encryption, among other tasks. One of the most well-known uses of network encryption is something called Secure Sockets Layer (SSL), which is used to encrypt web pages.

Q: How many well-known ports are there?
~ Port addresses apply to the TCP and UDP protocols and are divided into three categories or ranges: well-known, registered, and dynamic. Well-known ports range from 0 through 1,023 and are pre-assigned by the Internet Corporation for Assigned Names and Numbers (ICANN) for the use of major networking protocols. Well-known ports do not change, no matter what computer or operating system you use.

Q: What protocol defines the LLC and MAC sublayers?
~ The protocol that defines these two sublayers in the Data-Link layer is known as IEEE 802.2, defined in the greater IEEE 802 protocol set. The IEEE 802 protocols are written this way because they were first proposed by a standards organization known as the Institute of Electrical and Electronic Engineers.

Q: What are dynamic address ports also known as?
~ Dynamic ports range from 49,152 through 65,535 and are available for any application to use to communicate with any other application. Dynamic ports are also sometimes known as private ports and emphemeral ports

Q: List the four layers of the TCP/IP model.
~ Whereas the OSI model is based on an idealized network environment and does not match any real protocol suites, the TCP/IP model is built around the TCP/IP protocol suite. It includes the Application, Transport, Internet, and Network Access layers.

Q: What is the physical address known as on a host or device?
A: MAC address

Q: A __________ is a predefined and widely accepted set of rules that describe exactly how a specific task is to work in a network environment.
A: protocol
If right: A protocol is a predefined and widely accepted set of rules that describe exactly how a specific task is to work in a network environment. For communication to occur, both hosts must agree on the same protocol.

Q: The _____________ protocol asks for verification that a packet has successfully reached its destination.
A: connection-oriented
If right: Connection-oriented protocols ask for verification that a packet has successfully reached its destination before sending another packet out. Most Network layer protocols used in modern networks, such as IP, are of the connectionless variety. However, TCP, one of the most widely used protocols at the Transport layer, is actually a connection-oriented protocol.

Q: What is the opposite of encapsulation?
~ In networking, encapsulation is the process of taking data from a higher layer of the OSI model and carrying it down into the next layer. The reverse of this process is called de-encapsulation.

Q: When data is encapsulated, what is added at the beginning of data before it is sent to the next layer?
~ Each layer adds its own header in front of the header from the previous layer. This header contains information that describes what each layer of the OSI model is to do with the data.

Q: List at least one mnemonic used to describe the OSI model and match the corresponding OSI layers.
~ Mnemonics are used as a way to remember not-so-easy lists. In this case, each letter of the phase is the same letter for layer in the OSI model

Q: Explain what the OSI model is designed for.
~ The OSI Model was created as a framework and reference model for understanding how different networking technologies work together and interact. In this capacity, the OSI Model is an excellent place to start when trying to understand all the processes that are necessary for data to be moved around a data network.