Mixed Deck — All GATE Topics Flashcards
100 cards from real GATE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 20 Mixed Deck — All GATE Topics flashcards as text
What is encryption?
Answer: Converting data into coded format to prevent unauthorized access
Encryption transforms readable data into unreadable ciphertext using algorithms and keys, ensuring only authorized parties can access the information.
What does the term 'phantom read' refer to in transaction isolation?
Answer: A query returning rows that were inserted by another transaction mid-execution
A phantom read occurs when a transaction re-executes a range query and finds new rows inserted by another committed transaction.
The maximum window size in TCP using a 16-bit window field (without scaling) is:
Answer: 65,535 bytes
The 16-bit window field can represent values from 0 to 2^16 - 1 = 65,535 bytes.
A 4-bit ripple carry adder adds two 4-bit numbers. What is the maximum number of gate delays for carry propagation?
Answer: 8
Each full adder introduces 2 gate delays for carry, so 4 stages yield 8 gate delays total.
In a second-order control system, the damping ratio ζ = 0.5 corresponds to which response?
Answer: Underdamped
When 0 < ζ < 1 (here ζ = 0.5), the system is underdamped and exhibits oscillatory response.
What is root cause analysis?
Answer: Identifying the primary reason for a problem
Root cause analysis (RCA) is a systematic process for identifying the underlying, fundamental causes of a problem or undesirable event, rather than just addressing its symptoms. The goal of RCA is to implement solutions that prevent recurrence by eliminating the root cause. This leads to more effective and lasting problem resolution.
Which of the following correctly describes a 'lossless join decomposition'?
Answer: The natural join of the decomposed relations exactly reconstructs the original relation
A lossless join decomposition guarantees that joining the parts back on common attributes yields exactly the original relation with no spurious tuples.
A system is said to be observable if:
Answer: The initial state can be determined from the output over a finite time interval
Observability means the initial state x(0) can be uniquely determined from the output y(t) over a finite time interval [0, T].
What is the scientific method?
Answer: A systematic process for investigating phenomena through observation, hypothesis, experimentation, and analysis
The scientific method is the structured approach scientists use: observe, question, hypothesize, experiment, analyze data, and draw conclusions.
Which relational algebra expression represents the SQL: SELECT A FROM R WHERE B = 5?
Answer: π_A(σ_{B=5}(R))
First apply selection to filter rows (σ_{B=5}), then apply projection to keep only column A (π_A).
In Dijkstra's shortest path algorithm, which data structure gives the most efficient implementation?
Answer: Priority Queue (Min-Heap)
A priority queue (min-heap) allows efficient extraction of the minimum distance vertex in O(log V) time.
What is a zero-day vulnerability?
Answer: A security flaw unknown to the vendor with no available patch
Zero-day vulnerabilities are newly discovered security flaws that the vendor doesn't know about yet, giving them 'zero days' to fix it before potential exploitation.
In a full adder, the carry-out expression is:
Answer: AB + BCin + ACin
The carry-out of a full adder is Cout = AB + BCin + ACin (carry generated or propagated).
Which flip-flop is commonly used as the basic building block in shift registers?
Answer: D flip-flop
D flip-flops are the standard choice for shift registers because the output directly follows the D input on each clock edge.
Which protocol resolves an IP address to the corresponding MAC address on a local network?
Answer: ARP
ARP (Address Resolution Protocol) broadcasts an IP address query and receives the corresponding MAC address from the owning host.
In the context of query optimization, a 'selectivity' value close to 0 for a predicate means:
Answer: The predicate selects very few tuples
Selectivity is the fraction of tuples satisfying the predicate; a value near 0 means very few tuples match, making the predicate highly selective.
Which memory allocation strategy leads to external fragmentation?
Answer: Segmentation
Segmentation allocates variable-sized memory chunks, leading to external fragmentation as free memory becomes scattered in non-contiguous holes.
The 0/1 Knapsack problem with n items and capacity W, solved using dynamic programming, has time complexity:
Answer: O(n × W)
The DP table has n rows and W+1 columns, and each of the n×W cells is filled in O(1) time, giving O(n × W) total.
What is the time complexity of building a binary max-heap from an unsorted array of n elements using the linear-time build-heap procedure?
Answer: O(n)
Build-heap calls sift-down on n/2 internal nodes; since most are near the leaves, the total work sums to O(n) by the geometric series argument.
According to Rice's theorem, which of the following is decidable?
Answer: Whether a Turing machine has exactly 5 states
Rice's theorem applies to non-trivial semantic properties of a TM's language; the number of states is a syntactic property of the TM itself, which is decidable.