1.3 Exchanging data Flashcards
What is the bus network topology, and what are its advantages/disadvantages?
(1.3.3)
All devices connected to backbone cable.
Advantages:
- Cheap setup
- No additional hardware
Disadvantages:
- Backbone cable dependency
- Traffic increase 🡆 performance decrease
- All devices see data transmission
What is ACID within transaction processing? (1.3.2)
- Atomicity: processed in entirety or not at all
- Consistency: ensuring referential integrity
- Isolation: Simultaneous execution must make same results as sequence
- Durability: once executed, remains so
What does normalisation in databases aim to accomplish? (1.3.2)
- No redundancy
- Consistent data
- Problemless record addition/removal
- Accepts complex queries
What is server-side and client-side processing, and what are the advantages /
disadvantages of each? (1.3.4)
Server-side:
- Client sends data, server processes
- Advantages: improved security, consistency between clients, advanced
calculations, easily scaled - Disadvantages: availability/reliability required, limited responsiveness,
complex development
Client-side:
- Local device processing
- Advantages: quick execution, immediate feedback, server load reduced
- Disadvantages: security risks, processing power limitation
What is referential integrity? (1.3.2)
- No data redundancy
- Prevents foreign key pointing to non-existant primary key
What is packet / circuit switching, and what are the advantages / disadvantages
of each? (1.3.3)
Circuit:
- Direct-linked devices, maintained for conversation, data sending/receival same rate
- Advantages: arrival logically ordered, quick data reconstruction, no
communication delay - Disadvantages: bandwidth waste when unused, rate requires maintaining,
electrical interference
Packet:
- Data section communication across network, unlimited routes
- Advantages: multiple data arrival checks, many paths, WANs
- Disadvantages: time spent deconstructing / reconstructing
What is run-length and dictionary encoding? (1.3.1)
Run-length:
- Lossless, repeated values removed, replaced with 1 occurrence & repetition
amount - Relies on consecutive data pieces, otherwise little reduction
Dictionary:
- Lossless, frequent data pieces replaced with index
- Compressed data along dictionary
- Dictionary matches data to index
- Original data restorable
What are primary, foreign, and secondary keys? (1.3.2)
Primary: unique identifier, each object
Foreign: attribute linking 2 tables
Secondary: enables quicker searching, sorting by attribute
What is the mesh network topology, and what are its advantages/disadvantages?
(1.3.3)
Every node connects to every other node
Advantages:
- No cabling costs (if Wi-Fi)
- Node amount 🡅, reliability / speed 🡅
- Faster, no switch
Disadvantages:
- Maintenance difficult
- Wireless required (if Wi-Fi)
What is the star network topology, and what are its advantages/disadvantages?
(1.3.3)
Central node (switch), directs data flow, MAC identifies devices.
Advantages:
- Consistent performance
- Cable failure only affects 1 connection
- Data transmission faster
- Easy station addition
- No data collisions
Disadvantages:
- Expensive (switch / cabling)
- Switch-dependant
What are routers, switches, and gateways? (1.3.3)
Routers:
- Connects 2+ networks, has IP
- Determines best packet path
Switches:
- Directs data flow across network
- Only destination receives data
Gateways:
- Translate different network protocols, makes use same protocol
- Switches packet header protocol
What 3 main methods of strengthening network security exist, and how do they
work? (1.3.3)
Firewall:
- Prevents unauthorised network access
- Filters requests, ensures legitimacy
Proxy servers:
- Collecting / sending data on user behalf
- Protects user privacy (anonymity)
- Can prevent website access
Encryption:
- Secure data transmission across internet
What are the steps of protocol layering? (1.3.3)
Application:
- Specifies protocol used
Transport:
- Splits data into packets
- Labels with packet number
- Requests retransmission of lost
- Declares port
Network:
- Adds source / destination IP
- Routes packets
Link:
- Adds source / destination MAC
- Identifies device
What is the difference between lossy and lossless compression? (1.3.1)
Lossy: reduces size whilst removing some information
Lossless: reduces size without losing information
What is symmetric and asymmetric encryption? (1.3.1)
Symmetric:
- Sender / receiver share private key
- Key exchange distributes
- Both encrypts / decrypts data
- Key requires secrecy
Asymmetric:
- Two keys: public / private
- Public published anywhere
- Private kept secret
- Together creates key pair, mathematically-related
- Public key messages, only private key decrypts
- Encrypting with private key verifies sender, decryptable by public key
