ICAB CL Information Technology cheat sheet

Hardware tiers: CPU speed measured in GHz; main memory (RAM) is volatile; secondary storage (SSD/HDD) is non-volatile and retains data without power.

Data-representation units: 1 byte = 8 bits; 1 KB = 1024 bytes; 1 MB = 1024 KB; 1 GB = 1024 MB.

OSI model layers, bottom to top: Physical, Data Link, Network, Transport, Session, Presentation, Application (7 layers).

TCP is connection-oriented and reliable (sequencing, retransmission, acknowledgements); UDP is connectionless and does not guarantee delivery.

IPv4 address = 32 bits (four octets); IPv6 address = 128 bits. DNS resolves hostnames to IP addresses.

LAN spans a limited area under single administrative control; WAN spans large geographic areas; VPN creates an encrypted tunnel over a public network.

Cloud service models: IaaS supplies virtualized compute/storage; PaaS supplies a development platform; SaaS supplies a complete application to end users.

Database normal forms: 1NF removes repeating groups; 2NF removes partial dependencies; 3NF removes transitive dependencies on non-key attributes.

Backup types: full copies all data; incremental copies changes since the last backup of any type; differential copies changes since the last full backup.

SDLC phases in order: planning/feasibility, requirements analysis, design, development, testing, implementation, and maintenance.

Waterfall is sequential with fixed requirements; agile uses iterative increments and continuous stakeholder feedback.

ACID properties: Atomicity (all-or-nothing), Consistency (valid states only), Isolation (concurrent transactions do not interfere), Durability (committed data survives failure).

Primary key uniquely identifies a row and cannot be null; a foreign key references a primary key in another table and enforces referential integrity.

Data governance assigns ownership: data owner (accountable for the data), data steward (custodian of quality and definitions), data user (consumes data).

Master data is the core, shared reference data (customer, product, vendor); transactional data records business events.

Data-quality dimensions include accuracy, completeness, timeliness, consistency, validity, and uniqueness.

A data dictionary documents metadata: field names, data types, lengths, formats, and validation rules.

Batch processing collects transactions and processes them periodically; real-time (online) processing handles each transaction immediately.

Preventive controls stop errors before they occur (access restrictions, input validation, segregation of duties); detective controls find them after (reconciliations, exception reports); corrective controls fix them.

Segregation of duties separates authorization, custody of assets, and record-keeping so no single person controls an entire transaction.

Input controls: field check, validity check, limit/range check, reasonableness check, completeness check, check digit, and batch totals (hash, record count, financial total).

Processing controls: run-to-run totals, program-to-program reconciliation, and exception reports comparing actual to expected results.

Output controls: distribution logs, report retention, and reconciliation of report totals to source data.

General IT controls cover the IT environment (change management, access management, backup, operations); application controls apply to specific transactions.

ITIL change management requires request, assessment, approval, implementation, and post-implementation review; emergency changes follow a shortened but logged path.

Business continuity planning (BCP) restores critical operations; disaster recovery planning (DRP) restores IT infrastructure. RTO = maximum acceptable downtime; RPO = maximum acceptable data loss.

COSO internal control components: control environment, risk assessment, control activities, information and communication, and monitoring activities.

CIA triad: Confidentiality (authorized access only), Integrity (data is accurate and unaltered), Availability (systems accessible when needed).

Authentication factors: something you know (password), something you have (token), something you are (biometric); MFA combines two or more different factor types.

Symmetric encryption uses one shared key (fast, key-distribution problem); asymmetric encryption uses a public/private key pair (slower, solves key exchange).

Hashing is one-way and produces a fixed-length digest used for integrity; digital signatures use the sender's private key to prove authenticity and non-repudiation.

Firewall types: packet-filtering (header-based), stateful inspection (tracks connection state), application proxy (inspects content at the application layer).

IDS detects and alerts; IPS detects and blocks. Anti-malware, patching, and least privilege are preventive controls.

Risk formula: risk = likelihood × impact. Risk responses: avoid, reduce/mitigate, transfer (e.g., insurance), and accept.

Audit evidence is sufficient when it is relevant, reliable, and timely; evidence from independent external sources is more reliable than internally generated evidence.

SOC reports: SOC 1 covers controls relevant to financial reporting; SOC 2 covers security, availability, processing integrity, confidentiality, and privacy; SOC 3 is a general-use summary.