SQU IT Exit flashcards

36 cards. Read the term and the definition here. The deck at the top of this page is optional.

Big-O notation

A notation describing an upper bound on the growth rate of an algorithm's time or space as input size grows, ignoring constants and lower-order terms.

Recursion base case

The condition that stops recursive calls and returns a value without further recursion. Without a correct base case, recursion causes infinite calls and stack overflow.

Pass by value

A parameter-passing method where the callee receives a copy of the argument, so changes to the parameter do not affect the caller's variable. Java uses this for primitives and references.

Stack data structure

A last-in, first-out (LIFO) structure supporting push, pop, and peek in O(1). Used for function calls, undo operations, expression evaluation, and depth-first search.

Hash table

A data structure mapping keys to values via a hash function, giving average O(1) lookup, insert, and delete. Collisions are handled by chaining or open addressing.

Binary search tree

A binary tree where each node's left subtree holds smaller keys and right subtree larger keys. Search, insert, and delete average O(log n) but degrade to O(n) if unbalanced.

Merge sort

A divide-and-conquer sorting algorithm with O(n log n) worst-case time. It is stable but requires O(n) auxiliary space, making it less memory-efficient than quicksort.

Dijkstra's algorithm

A single-source shortest-path algorithm for weighted graphs with non-negative edges. Using a priority queue, it runs in O((V+E) log V) and fails with negative edge weights.

ACID properties

Four transaction guarantees: Atomicity (all or nothing), Consistency (constraints preserved), Isolation (concurrent transactions do not interfere), and Durability (committed changes persist through failures).

Third normal form

A relation is in 3NF when it is in 2NF and has no transitive dependency of a non-key attribute on the primary key. It reduces redundancy and update anomalies.

SQL WHERE vs HAVING

WHERE filters individual rows before grouping; HAVING filters groups after GROUP BY and aggregation. Aggregate conditions such as COUNT(*) > 5 belong in HAVING.

Foreign key

A column or set of columns that references a primary key in another table, enforcing referential integrity. It may be NULL unless declared NOT NULL.

Clustered index

An index that determines the physical order of rows in a table. A table can have only one clustered index; non-clustered indexes are separate structures pointing to rows.

TCP three-way handshake

Connection setup using SYN, SYN-ACK, and ACK segments. It synchronizes sequence numbers and confirms both sides are ready before data transfer begins.

Symmetric vs asymmetric encryption

Symmetric encryption uses one shared key and is fast for bulk data (AES). Asymmetric encryption uses a public/private key pair, is slower, and supports key exchange and digital signatures (RSA).

Digital signature

A hash of a message encrypted with the sender's private key. It provides authentication, integrity, and non-repudiation, and is verified with the sender's public key.

CIA triad

The core security model: Confidentiality (only authorized parties access data), Integrity (data is accurate and unaltered), and Availability (systems and data are accessible when needed).

Private IP ranges

Non-routable IPv4 blocks reserved for internal networks: 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. They require NAT to reach the public internet.

Process vs thread

A process has its own address space and resources; threads within a process share memory and resources but have separate stacks. Thread context switching is cheaper than process switching.

Deadlock conditions

Four simultaneous conditions cause deadlock: mutual exclusion, hold and wait, no preemption, and circular wait. Breaking any one prevents deadlock.

Virtual memory paging

A technique dividing memory into fixed-size pages and frames, allowing programs larger than physical RAM. A page fault loads a missing page from disk; excessive faults cause thrashing.

Round Robin scheduling

A preemptive CPU scheduling algorithm giving each process a fixed time quantum in circular order. It is fair and responsive but adds overhead from frequent context switches.

Coupling and cohesion

Coupling measures dependence between modules (low is desirable); cohesion measures how focused a module's responsibilities are (high is desirable). Good design targets low coupling and high cohesion.

Verification vs validation

Verification checks that the product conforms to its specification ('building it right'). Validation checks that it meets user needs ('building the right product').

Agile vs Waterfall

Waterfall is sequential with heavy upfront documentation and late testing. Agile is iterative, delivering increments in short sprints with continuous customer feedback and testing.

Black-box testing

Testing that exercises functionality without knowledge of internal code structure, based on inputs and expected outputs. It complements white-box testing, which examines internal paths.

HTTP status code classes

2xx success, 3xx redirection, 4xx client error, 5xx server error. Examples: 200 OK, 301 Moved Permanently, 404 Not Found, 500 Internal Server Error.

REST statelessness

A REST constraint requiring each request to contain all information needed to process it, with no client session stored on the server. State is carried by the client, often via tokens.

SQL injection prevention

Use parameterized queries or prepared statements, validate and sanitize input, apply least-privilege database accounts, and avoid concatenating user input into SQL strings.

MVC architecture

A pattern separating Model (data and business logic), View (presentation), and Controller (input handling). It improves separation of concerns and testability in web and mobile apps.

Triple constraint

The project management triangle of scope, time, and cost. Changing one typically requires adjusting the others, and quality is affected when the balance is not managed.

Critical path

The longest sequence of dependent activities in a project network, determining the minimum project duration. Activities on it have zero float, so any delay delays the project.

Earned Value Management

A project performance method using PV, EV, and AC. Cost Performance Index = EV/AC and Schedule Performance Index = EV/PV; values below 1 mean over budget or behind schedule.

Whistleblowing justification

Disclosure of wrongdoing is ethically justified when serious harm is likely, internal channels have been exhausted, evidence is solid, and the disclosure is proportionate and targeted.

Tuckman team stages

Five stages of team development: forming (orientation), storming (conflict), norming (agreement), performing (productive work), and adjourning (disbanding).

Data minimization principle

A privacy principle requiring collection of only the personal data necessary for a stated purpose, retained no longer than needed and used only for that purpose.