Exam Tutorial Flashcards
List the 7 Layers of the OSI Model
Application, presentation, session, transport, network, data-link, physical
Briefly describe the purpose of each layer
application, network process to application
presentation data representation and encryption
Session interhost communication
Transport End-to-end connections and reliability
Network Path determination and IP (Logical Addressing)
Data Link MAC and LLC (Physical Addressing)
Physical Media, Signal and Binary Transmission
Draw the bus, star, ring , mesh and hybrid physical topologies
Diagrams
Draw packet, message, circuit switched networks, describe how they operate and give an example of each
Diagrams
Circuit: used to connect 2 devices, a continuous, physical link is established to carry transmissions between the end points
Message: Transmitted is in a set format and contains a header showing destination and originating addresses. The message is transmitted to an access node and then a trunk node sending the message along the correct route however relying on disc storage space and causing delays to the message.
Packet: The message is disassembled and each packet labelled with the destination address they are then sent via different network paths and then reassembled in the correct order once at the intended target.
Give a private IP address
192.168.8.15
What are the major internet working devices, what layer of the OSI model do they operate and what role do they carry out
Router, Gateway, Bridges, Switches, Hubs, Repeaters
Repeaters: Send network signals over long distances : operate physical layer
Bridges: Connects two or more Network segments together Data-link layer
Routers: Filter Traffic across a network segment and ensures packets go to the correct destination therefore reducing network traffic
Gateway: Application to transport layer , are used to translate between protocols and data formats
Define attenuation
The signal that is lost through a wire or a medium
Define Bandwidth
The amount of signal that can be transmitted over a network cable at one time
Give the advantages and disadvantages of UTP, STP , fibre and COAX
UTP (Unshielded Twisted Pair)
Cheap, Small in diameter, Doesn’t require special adapter, easy to install, susceptible to crosstalk and EMI
No shield is fitted
STP (shielded Twisted Pair)
Shield is fitted
Electrically grounded therefore less susceptible to EMI and crosstalk, Slightly bigger diameter than UTP, Greater bandwidth than UTP, l more difficult to install, special connectors required
Fibre
Non susceptibility to EMI
No susceptibility to crosstalk
Much greater bandwidth
Greater cost
More difficult to install
Special Connectors required
More fragile
COAX
Shielded single thick copper wire surrounded by an insulator. Very resistant to EMI, very old system
Draw and explain VLAN
Virtual Local Area network
What does packet filtering check
Packet’s source and destination address, Protocol, Port number
Define a Combat System
Set of person and machinery which comprises the fighting capability of the vessel. Subsystems include, sensors, weapons, intelligence and information sources
Define a combat management System
Is a military management system, comprising a close integration of person and machines which together enable: comprehensive tactical picture, Formulation , issuing and modification of directives
What are the time critical components of naval C2 and their definitions?
Tactical Data Fusion Formulation of a coherent picture by fusing together in real time all the information available on board ship from a wide range of disparate sources.
Situation Assessment Derivation of intelligent assessment, in tactical terms, of the environment of a single ship or groups of ships.
Resource Allocation Deployment of resources necessary in the prevailing circumstances
Resource Planning Deployment of resources in anticipation of a future situation using knowledge, including intelligence, to predict what might happen and how own forces should be deployed to counter any threats.
What are the sub-systems of the CMS and what timescales do they operate over?
Long Term Major Sea Areas, Days to Months
Medium Term Range of interest of the order of a thousand miles, hours to days
Current seconds to minutes, within few hundred miles
Immediate minutes to fractions of seconds, sudden changes in the environment
