Below are twenty example questions drawn from across all ten NSCT subjects — two per subject, mixed across Easy, Medium, and Hard difficulty levels. Every question includes the full explanation you would see during live practice. Skim through them to get a feel for the question style and depth before starting your first real quiz.
3,360+ total MCQs · View subject page
An algorithm runs in O(n log n) time. If it takes 1 second for n = 1000, approximately how long will it take for n = 1,000,000?
n grows by 1000x, log n grows by roughly 2x (from ~10 to ~20), so total work grows by ~2000x. That puts the runtime near 2000 seconds — not the linear extrapolation (1000s) and nowhere near the O(n^2) answer (1,000,000s).
A function is called recursively with the rule f(n) = f(n/2) + 1, base case f(1) = 0. What does f(n) compute for n = 2^k?
Each recursive call halves n and adds 1 to the result. Starting from n = 2^k, you need exactly k halvings to reach 1, so f(2^k) = k = log₂ n. Recognizing this is the core pattern behind binary search and many divide-and-conquer complexity derivations.
3,570+ total MCQs · View subject page
You train a model that gets 99% training accuracy but 62% test accuracy. What is most likely happening, and what is the first fix to try?
A large gap between training and test accuracy is the textbook signature of overfitting. The first line of defence is regularization (L1/L2, dropout) or increasing the training data. Underfitting would show low accuracy on both sets. Data leakage usually inflates test accuracy, not the reverse.
In a fraud detection dataset where 1% of transactions are fraudulent, which metric is MOST misleading if used alone?
A model that predicts 'not fraud' for every transaction scores 99% accuracy on this dataset while catching zero fraud. Accuracy hides class imbalance; precision and recall (and their harmonic mean, F1) reveal it.
2,100+ total MCQs · View subject page
A device has IP address 192.168.1.130 with subnet mask 255.255.255.192. What is the network address?
A /26 mask (255.255.255.192) gives 64-host blocks: .0, .64, .128, .192. The address .130 falls into the .128 block, so the network address is 192.168.1.128. The last valid host in this subnet is .190 and the broadcast is .191.
Which statement about TCP and UDP is CORRECT?
TCP is connection-oriented, reliable, and guarantees in-order delivery via sequence numbers and retransmissions. UDP is connectionless, unreliable, and delivers datagrams in whatever order they arrive. Only TCP uses the three-way handshake; UDP has no handshake at all.
2,520+ total MCQs · View subject page
Which data structure is BEST for implementing a browser's 'back' button?
'Back' undoes the most recent action first — that is LIFO behaviour, which is exactly what a stack provides. A queue would give you the oldest page first, the reverse of what you want. Priority queues and hash tables don't encode action ordering.
What is the worst-case time complexity of inserting n elements into an initially empty binary search tree, assuming no rebalancing?
If elements arrive in sorted order, each insert walks the full height of the tree, which degenerates into a linked list of length n. That makes the i-th insert O(i), summing to O(n²). With self-balancing (AVL, red-black), the worst case drops to O(n log n).
2,520+ total MCQs · View subject page
Which of the following is NOT one of the four Coffman conditions required for deadlock?
The four Coffman conditions are mutual exclusion, hold and wait, NO preemption, and circular wait. Preemption itself actually PREVENTS deadlock — if we can forcibly take resources from a process, the hold-and-wait chain breaks. The trap here is reading quickly and missing the 'NO'.
A system uses 32-bit virtual addresses with 4 KB pages. How many bits are needed for the page offset?
A 4 KB page holds 4096 = 2^12 bytes, so the offset within a page takes 12 bits. The remaining 32 − 12 = 20 bits identify the page number, giving 2^20 = roughly 1 million pages in the virtual address space.
3,570+ total MCQs · View subject page
Which HTTP status code indicates a resource has moved PERMANENTLY to a new URL?
301 Moved Permanently tells clients (and search engines) to update their bookmarks and index entries to the new URL. 302 and 307 are temporary redirects. 308 is also a permanent redirect but preserves the HTTP method, while 301 historically allowed clients to change POST to GET.
In JavaScript, what does the following output? console.log([] == false)
With loose equality (==), both sides are coerced. [] converts to '' (empty string), which converts to 0. false also converts to 0. So 0 == 0 → true. This is why style guides push === — loose equality's coercion rules are a reliable trap.
3,360+ total MCQs · View subject page
In Scrum, which role is responsible for maximizing the value of the work done by the development team?
The Product Owner owns the backlog and prioritizes features by business value. The Scrum Master facilitates the process and removes impediments but does not set priorities. There is no 'Development Team Lead' or 'Project Manager' in the official Scrum framework.
Which testing level would catch a bug where two correctly-tested modules fail to communicate due to a mismatched data format?
Unit tests verify a single module in isolation — they would not exercise the interface between modules. Integration tests specifically target the contracts between modules, which is exactly where this bug lives. Acceptance and regression testing operate at higher levels and usually catch this too, but integration is the first and most economical line of defence.
3,360+ total MCQs · View subject page
In C, what does the following print? int x = 5; printf("%d", x++); printf("%d", ++x);
x++ is post-increment: it uses the current value (5) then increments to 6. ++x is pre-increment: it increments first (to 7) then uses that value. So the output is '5' followed by '7'. Any language with both operators will behave this way for primitive integers.
Which OOP concept is demonstrated when a subclass provides a different implementation of a method already defined in its parent class?
Overriding is exactly this: the subclass replaces the parent's implementation while keeping the same signature, and the choice of which version runs is made at runtime (dynamic dispatch). Overloading is defining multiple methods with the same name but different signatures in the same class, resolved at compile time.
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A table has columns (A, B, C). If A → B and B → C, which normalization form removes this dependency chain?
3NF specifically targets transitive dependencies — situations where a non-key column (B) determines another non-key column (C). Splitting the table so that C lives with its determinant B, separate from A, satisfies 3NF. 2NF removes partial dependencies on composite keys; BCNF tightens 3NF further for edge cases.
Which SQL clause filters GROUPS after aggregation?
HAVING is the post-aggregation filter. WHERE filters rows before they enter the aggregation. GROUP BY defines the grouping but does not filter. FILTER is a PostgreSQL extension used inside aggregate functions, not a top-level filtering clause.
3,360+ total MCQs · View subject page
Which attack exploits user trust in a website to execute unintended actions using the user's authenticated session?
CSRF tricks an authenticated user's browser into sending a request the user did not intend (e.g., transfer money while logged into a bank site). XSS runs attacker code in the user's browser. SQLi attacks the database via crafted input. MITM intercepts traffic in transit. The defining CSRF trait is 'uses the existing session without the user's knowledge'.
What is the primary reason passwords should be stored as salted hashes rather than as encrypted values?
Both reasons matter. One-way hashing means a database leak does not expose plaintext passwords, and the absence of a shared key means there is no secondary secret whose compromise would unlock everything. Salting additionally defeats rainbow tables by making each hash unique even for identical passwords.
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