Information System Fundamentals
Domain 1, Information System Fundamentals, tests whether you can name the parts of a system, place a component in the right layer, and perform the small calculations (address space, RAID capacity, normalization level) that appear as single-choice items. Items are usually scenario-framed: a described system must be classified, or an observed symptom attributed to hardware, software, data, procedure or network.
The five components
- Hardware: physical devices - servers, storage, network gear.
- Software: system software (OS, drivers, virtualisation layer) and application software.
- Data: the records themselves plus the schema describing them.
- Procedures: documented operating rules - backup schedules, change steps, escalation paths.
- People: users, operators, administrators. A scenario where nobody knows who approves restores is a procedure and people defect, not a hardware one.
Hardware and software basics
CPU = control unit + ALU + registers; cache runs L1 (fastest, smallest) to L3. Main memory is volatile; ROM and flash retain content. Addressable memory = 2^(address bus width) bytes. RAID 0 stripes with no redundancy, RAID 1 mirrors, RAID 5 survives one disk failure using distributed parity, RAID 10 mirrors then stripes. An OS, device driver or hypervisor is system software; a DBMS is normally classed as system software in the syllabus; payroll, ERP and office suites are application software.
Networks and databases
OSI layers: physical, data link, network, transport, session, presentation, application; TCP/IP folds the top three into application. IP address plus mask separates network and host portions; DNS resolves names, DHCP leases addresses. Relational terms: relation (table), tuple (row), attribute (column); a primary key identifies uniquely, a foreign key enforces referential integrity. Normalization: 1NF atomic values, 2NF no partial dependency on part of a composite key, 3NF no transitive dependency. Transactions obey ACID.
Worked example
A server has a 36-bit physical address bus. Addressable memory = 2^36 bytes. Since 2^30 = 1 GiB, 2^36 = 2^6 × 2^30 = 64 GiB. Reasoning shown: convert the exponent into binary units, never decimal GB. Options such as 36 GB, 64 GB or 72 GiB are all wrong.
Traps
- Treating normalization as a performance technique: it removes redundancy and update anomalies but adds joins, so read speed may drop.
- Confusing atomicity (all-or-nothing) with consistency (constraints still hold).
- Calling a DBMS application software, or calling firmware hardware.
- Assuming RAID replaces backup; it protects against disk failure only.