WA Computer Science ATAR Unit 1 Definitions Worksheet: Standard Algorithms and Network Communications (Modules 315–470)
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Key terms
Write what each term means, in your own words.
1
O(n^2)
2
communication model
3
network layer model
4
OSI model
5
TCP/IP to OSI mapping
6
encapsulation
7
device layer
8
topology
9
network design factors
10
scalability
11
network design
12
file path
13
cron
14
shell script
15
shutil.copy(src, dst)
Answer Key
WA Computer Science ATAR Unit 1 · Modules 315–470 · Student wording will vary for definitions
1O(n^2) — Bubble and selection sort both make about n squared comparisons, so doubling n quadruples the work, but selection sort makes far fewer swaps.
2communication model — How devices share the work of requesting and providing data: client-server uses dedicated servers, while peer-to-peer lets every device do both.
3network layer model — Splits network communication into layers that each do one job and talk only to the layers above and below, so vendors interoperate, layers change alone and faults are easier to find.
4OSI model — A seven-layer network model: physical, data link, network, transport, session, presentation, application. Layer 1 is physical (bottom) and layer 7 is application (top).
5TCP/IP to OSI mapping — Each TCP/IP layer covers one or more OSI layers: Application = OSI application, presentation and session; Network Access = physical and data link; Transport and Internet match one each.
6encapsulation — Each layer on the sender adds its own header (and sometimes a trailer) as data moves down the layers. The receiver removes them in reverse order, which is called decapsulation.
7device layer — The OSI layer a device works at: hubs at layer 1, NICs and access points at layers 1-2, switches at 2, routers at 3, and firewalls and proxies at layers 3 to 7.
8topology — The layout of a network: bus shares one cable, ring passes data around a loop, and mesh links devices by many paths.
9network design factors — The needs and limits, such as cost, performance, reliability, security, scalability and user needs, that decide which devices, cables and layout a network should use.
10scalability — A scalable network can grow in users, devices and traffic without a major redesign, for example by planning for growth, keeping spare switch ports and having an upgrade path.
11network design — Turning user requirements into a plan by choosing devices, media, topology, IP addressing and security controls, then justifying each choice.
12file path — The location of a file in the folder tree, written from the root (absolute, e.g. /home/sam/file.txt) or from the current folder (relative).
13cron — A scheduler that runs a command or script at set times without a person starting it, such as a nightly backup. Windows Task Scheduler does the same job.
14shell script — A text file of shell commands, such as cp, mv or rm, that run in order each time the script is run, so file tasks like backups can be automated.
15shutil.copy(src, dst) — Python call that copies a file to a backup folder. Put a datetime timestamp in the new name so old backups are not overwritten, and a scheduler can then run the script.