CNIT 240
CNIT 240 Final Review Exam Questions
And Answers 100% Solved.
What are the components of communications? - ✔✔✔ - - source
- destination
- message
- transmission medium
What is a layered approach to communications? - ✔✔✔ - - provides a logical breakdown in
functions, operations, responsibilities, maintainance, and management of a system
- each layer performs a specific set of functions or tasks
- layers rely on other layers to perform their specified tasks
- use defined interfaces to communicate between layers
- provides the opportunity to improve, enhance, replace components of the system without
need to replace entire system
List some communication reference models - ✔✔✔ - - Open System Interconnection (OSI)
- TCP/IP
- Input-Process-Output (IPO)
What is the OSI model? - ✔✔✔ - - defines 7 layers in order to describe end-to-end
communications between any two systems
- provides open interconnections between layers (ie. can support multi-vendor environments)
What are some of the OSI model's rules for communication? - ✔✔✔ - - communication
between layers is handled in specified (defined) manner
CNIT 240 Page 1
,CNIT 240
- each layer is only able to communicate with its adjacent layers
- each layer relies on layers below it to perform their specified function
- each layer relies on layers above it to perform their specified function
What are the 7 layers of the OSI model? - ✔✔✔ - "Please do not throw sausage pizza away"
(bottom to top)
- physical layer
- data link layer
- network layer
- transport layer
- session layer
- presentation layer
- application layer
What is the physical layer of the OSI model? - ✔✔✔ - - responsible for transmission and
receipt of bit stream to/from nodes
- solely concerned with signaling techniques (activating, maintaining, terminating physical
circuit)
- electrical, mechanical, and functional control of data communications circuits in networks
- will pass received information up to layer 2
- does NOT include the physical media!!
- passes bit stream to layer 2 for frames/cells construction
- provides buffering for frame fragments
- performs a simple "error-detection" routine (at signal level)
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,CNIT 240
What is the data link layer of the OSI model? - ✔✔✔ - - responsible for providing POINT-TO-
POINT validity of the data (via point-to-point checking/correction; CRC is most common
approach)
- not all LAN architectures can support reliable delivery (must verify frame integrity;
acknowledge that each frame was received intact)
- UTILIZES FRAMES!
- converts data to frames
- independent address architecture from other layers
- procedures and protocols for reliably operating communication links
What are the data link sub-layers? - ✔✔✔ - MAC functions
- ensures access to shared medium
- responsible for framing data prior to physical transmission
- transmitting frames between end nodes using functionality of physical-layer devices
LLC functions
-provides reliable delivery of layer 3 PDUs through service access points
- organizing an interface to network layer, which is directly adjacent to it
- ensures reliable frame delivery with predefined reliability level
What is the network layer of the OSI model? - ✔✔✔ - - enables INTERNETWORKING!
- establishes routes between source and destination NETWORKS
- END-TO-END!
- relies on higher layer protocols for error detection and correction
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, CNIT 240
- UNRELIABLE!
- not logically required for connectivity on a LAN (layer 3 services are often required by
applications that do interface directly with layer 2)
- utilizes PACKETS (reliable)! or datagrams (unreliable)
- converts DATA TO PACKETS!
- includes routable/routed protocols (routable: IP, IPX, AppleTalk; routed: RIP, OSPF, BGP)
What is the transport layer of the OSI model? - ✔✔✔ - - responsible for HOST-TO-HOST
integrity of transmission
- functionality provided beyond LAN segment
- detects damanged or lost packets and generates retransmit requests (SYN, SYN-ACK, ACK, etc)
- re-sequences packets
- depends on layer 3 protocol being used (TCP, UDP, etc)
- utilizes MESSAGES or SEGMENTS
- converts DATA TO SEGMENTS
What is the session layer of the OSI model? - ✔✔✔ - - establishes, maintains, and terminates
HOST-TO-HOST INTERACTIVE SESSIONS
- used to uniquely identify a service, application, or function on a host via PORTS
- COMMUNICATION COORDINATION!
What is the presentation layer of the OSI model? - ✔✔✔ - - responsible for managing the way
data is presented
- code conversion/translation (ASCII, EBCDIC, Unicode, etc; encryption & text compression)
- data syntax and structure
CNIT 240 Page 4
CNIT 240 Final Review Exam Questions
And Answers 100% Solved.
What are the components of communications? - ✔✔✔ - - source
- destination
- message
- transmission medium
What is a layered approach to communications? - ✔✔✔ - - provides a logical breakdown in
functions, operations, responsibilities, maintainance, and management of a system
- each layer performs a specific set of functions or tasks
- layers rely on other layers to perform their specified tasks
- use defined interfaces to communicate between layers
- provides the opportunity to improve, enhance, replace components of the system without
need to replace entire system
List some communication reference models - ✔✔✔ - - Open System Interconnection (OSI)
- TCP/IP
- Input-Process-Output (IPO)
What is the OSI model? - ✔✔✔ - - defines 7 layers in order to describe end-to-end
communications between any two systems
- provides open interconnections between layers (ie. can support multi-vendor environments)
What are some of the OSI model's rules for communication? - ✔✔✔ - - communication
between layers is handled in specified (defined) manner
CNIT 240 Page 1
,CNIT 240
- each layer is only able to communicate with its adjacent layers
- each layer relies on layers below it to perform their specified function
- each layer relies on layers above it to perform their specified function
What are the 7 layers of the OSI model? - ✔✔✔ - "Please do not throw sausage pizza away"
(bottom to top)
- physical layer
- data link layer
- network layer
- transport layer
- session layer
- presentation layer
- application layer
What is the physical layer of the OSI model? - ✔✔✔ - - responsible for transmission and
receipt of bit stream to/from nodes
- solely concerned with signaling techniques (activating, maintaining, terminating physical
circuit)
- electrical, mechanical, and functional control of data communications circuits in networks
- will pass received information up to layer 2
- does NOT include the physical media!!
- passes bit stream to layer 2 for frames/cells construction
- provides buffering for frame fragments
- performs a simple "error-detection" routine (at signal level)
CNIT 240 Page 2
,CNIT 240
What is the data link layer of the OSI model? - ✔✔✔ - - responsible for providing POINT-TO-
POINT validity of the data (via point-to-point checking/correction; CRC is most common
approach)
- not all LAN architectures can support reliable delivery (must verify frame integrity;
acknowledge that each frame was received intact)
- UTILIZES FRAMES!
- converts data to frames
- independent address architecture from other layers
- procedures and protocols for reliably operating communication links
What are the data link sub-layers? - ✔✔✔ - MAC functions
- ensures access to shared medium
- responsible for framing data prior to physical transmission
- transmitting frames between end nodes using functionality of physical-layer devices
LLC functions
-provides reliable delivery of layer 3 PDUs through service access points
- organizing an interface to network layer, which is directly adjacent to it
- ensures reliable frame delivery with predefined reliability level
What is the network layer of the OSI model? - ✔✔✔ - - enables INTERNETWORKING!
- establishes routes between source and destination NETWORKS
- END-TO-END!
- relies on higher layer protocols for error detection and correction
CNIT 240 Page 3
, CNIT 240
- UNRELIABLE!
- not logically required for connectivity on a LAN (layer 3 services are often required by
applications that do interface directly with layer 2)
- utilizes PACKETS (reliable)! or datagrams (unreliable)
- converts DATA TO PACKETS!
- includes routable/routed protocols (routable: IP, IPX, AppleTalk; routed: RIP, OSPF, BGP)
What is the transport layer of the OSI model? - ✔✔✔ - - responsible for HOST-TO-HOST
integrity of transmission
- functionality provided beyond LAN segment
- detects damanged or lost packets and generates retransmit requests (SYN, SYN-ACK, ACK, etc)
- re-sequences packets
- depends on layer 3 protocol being used (TCP, UDP, etc)
- utilizes MESSAGES or SEGMENTS
- converts DATA TO SEGMENTS
What is the session layer of the OSI model? - ✔✔✔ - - establishes, maintains, and terminates
HOST-TO-HOST INTERACTIVE SESSIONS
- used to uniquely identify a service, application, or function on a host via PORTS
- COMMUNICATION COORDINATION!
What is the presentation layer of the OSI model? - ✔✔✔ - - responsible for managing the way
data is presented
- code conversion/translation (ASCII, EBCDIC, Unicode, etc; encryption & text compression)
- data syntax and structure
CNIT 240 Page 4
