Domain 4 - Communication and Network Security Flashcards
3 Communications control mode
Simplex : one-way communication (One systems transmits, the other listen)
Half-duplex : communication sends or receives at one time only (only one system can transmit at a time)
Full-duplex : communication send and receive simultaneously (both system can transmit /receive simultaneously)
Circuit Switching vs Packet Switching
Circuit switching:
> Expensive but always available, used less often
> a dedicated communication channel through the network
> the circuit guarantees the full bandwidth
> the circuit functions as if the nodes were physically connected a cable
Packet switching:
> Cheap, but no capacity guarantee, very widely used today
> Data is sent in packet, but take multiple different paths to the destination
> The packets are reassembled at the destination
!! QoS (Quality of Service) gives traffic priority over other traffic
Most commonly VOIP (Voice over IP) or other UDP traffic needing close to real time communication, other non real time traffic is down prioritized, the 0.25 s delay wont be notices
Types of Network
> Personal Area Network (PAN)
computer network used for communication among computer and other information technological devices close to one person (PCs, printer, scanners, consoles), can include wired (USB and FireWire) and wireless device (Bluetooth and Infrared)
Local Area Network (LAN)
A network that connect computer and device in a limited geographical area such as a home, school, office building, or campus. Each computer or device on the network is a node
Metropolitan Area Network (MAN)
A large computer network that usually spans a city or large campus
Wide Area Network (WAN)
Computer network that cover large geographic area such as city, country, even intercontinental distance. Combines many types of media such as telephone lines, cables, and air waves
Virtual Private Network (VPN)
A VPN network send private data over an insecure network, most often the internet
Global Area Network (GAN)
is a network used for supporting mobile users across number of wireless LANs, satellite coverage areas
What is OSI (Open System Interconnect) Model
A layered network model that standardizes the communication functions of a telecommunication or computing system.
7 Layers (7-1) Australia Post Sucks iT Never Delivers Parcels 7. Application 6. Presentation 5. Session 4. Transport 3. Network 2. Data Link 1. Physical
What is PDU (Protocol Data Unit)?
a specific block of information transferred over a network, it can be form as Data, Segments, Packets, Frames, or Bits
Application Layer Responsibility
for INTERFACING user applications, network services, or the operating system with the protocol stack. The software application is not located within this layer; rather, the protocols and services required to transmit files, exchange messages, connect to remote terminals, and so on are found here.
Presentation Layer Responsibility
for TRANSFORMING DATA into a format that any system following the OSI model can understand. It imposes common or standardized structure and formatting rules onto the data. The Presentation layer is also responsible for encryption and compression.
