Question 1

What is the difference between SDLC and STLC?

Accepted Answer

SDLC is the full lifecycle for building software, from requirements to maintenance. STLC is the testing lifecycle that runs inside SDLC and covers how testing is planned, designed, executed, and closed.

Question 2

What is the difference between verification and validation?

Accepted Answer

Verification checks whether we are building the product right, through reviews, walkthroughs, and inspections without executing code. Validation checks whether we built the right product by actually executing the software against user needs.

Question 3

What is the difference between severity and priority? Give examples.

Accepted Answer

Severity is the impact of a defect on the system, usually set by QA. Priority is how urgently it must be fixed, usually set by the product owner or lead based on business need.

Question 4

Explain the bug life cycle.

Accepted Answer

A bug moves from New to Assigned, then Open while the developer works on it, then Fixed, and back to QA for Retest. If it passes it is Verified and Closed; if not it is Reopened.

Question 5

What is the difference between smoke and sanity testing?

Accepted Answer

Smoke testing is a broad, shallow check on a new build to confirm critical flows work and the build is stable enough for further testing. Sanity testing is a narrow, focused check after a small change or fix to confirm that specific area works.

Question 6

What is the difference between retesting and regression testing?

Accepted Answer

Retesting confirms a specific defect is fixed by re-running the failed test case. Regression testing checks that the fix or a new change has not broken existing, previously working functionality.

Question 7

What is the difference between functional and non-functional testing?

Accepted Answer

Functional testing checks what the system does against requirements, like login or checkout. Non-functional testing checks how well it does it, such as performance, security, usability, and compatibility.

Question 8

Explain Boundary Value Analysis with an example.

Accepted Answer

BVA tests values at and around the edges of a valid range because defects cluster at boundaries. For an age field accepting 18 to 60, I test 17, 18, 19, 59, 60, and 61.

Question 9

What is Equivalence Partitioning?

Accepted Answer

Equivalence Partitioning divides inputs into groups that the system should treat the same way, then tests one value from each group. For age 18 to 60, partitions are below 18 (invalid), 18 to 60 (valid), and above 60 (invalid).

Question 10

When would you use decision table testing?

Accepted Answer

I use decision tables when the output depends on combinations of conditions, like business rules for discounts or loan approval. Each column is a rule combining condition values with the expected action.

Question 11

What does a test plan contain?

Accepted Answer

A test plan defines scope, approach, resources, schedule, and risks for testing a release. It is the agreement on what will and will not be tested and how we decide we are done.

Question 12

What makes a good test case?

Accepted Answer

A good test case is clear, independent, traceable to a requirement, and has precise steps, test data, and an expected result that anyone can execute and judge pass or fail.

Question 13

What is the role of QA in an Agile Scrum team?

Accepted Answer

In Scrum, QA is part of the team from refinement onwards, clarifying acceptance criteria, testing stories within the sprint, and automating regression. Quality is shared, but QA drives the testing mindset.

Question 14

What is exploratory testing and when is it useful?

Accepted Answer

Exploratory testing is simultaneous learning, test design, and execution without pre-written scripts. It is useful for new features, unclear requirements, and finding issues scripted tests miss.

Question 15

What is UAT and who performs it?

Accepted Answer

User Acceptance Testing is the final phase where business users or clients verify the software meets their needs in a production-like environment before go-live. QA usually supports with data, environments, and defect triage.

Question 16

A developer says your bug cannot be reproduced. What do you do?

Accepted Answer

I re-run it myself, then check environment differences such as build, browser, data, user role, and config. I add exact steps, logs, screenshots or a video and, if needed, reproduce it together with the developer.

Question 17

How do you decide when to stop testing?

Accepted Answer

Testing never proves zero defects, so I stop based on agreed exit criteria and risk: critical scenarios pass, no open critical or high bugs, coverage targets met, and the business accepts the remaining risk.

Question 18

How would you test with limited time before a release?

Accepted Answer

I use risk-based testing: prioritise by business impact and likelihood of failure, cover critical user journeys and changed areas first, and clearly report what was not tested.

Question 19

A critical bug was found in production that QA missed. How do you handle it?

Accepted Answer

First help reproduce and verify the hotfix quickly. Then do a blameless root cause analysis: why it escaped, whether it was a missing requirement, test gap, or environment difference, and add tests or process changes to prevent recurrence.

Question 20

How do you test when there are no proper requirements?

Accepted Answer

I gather information from the product owner, developers, existing app behaviour, competitor products, and user stories, then document my assumptions and get them confirmed. Exploratory testing helps build understanding quickly.

Question 21

What is software testing and why is it needed?

Accepted Answer

Software testing is evaluating a product to find defects and confirm it meets requirements and user needs. It reduces risk, gives stakeholders information about quality, and finding bugs early is far cheaper than fixing them in production.

Question 22

What are the phases of the STLC?

Accepted Answer

The Software Testing Life Cycle has six phases: requirement analysis, test planning, test case design, test environment setup, test execution, and test closure. Each phase has its own entry and exit criteria and deliverables.

Question 23

What is the difference between a test scenario, test case and test script?

Accepted Answer

A test scenario is a high-level one-liner of what to test, like 'verify login functionality'. A test case is the detailed set of preconditions, steps, data and expected result for one condition of that scenario. A test script usually means an automated or very detailed step-by-step version.

Question 24

What is the difference between black-box, white-box and grey-box testing?

Accepted Answer

Black-box testing checks behaviour against requirements without knowing the code. White-box testing designs tests from the internal code structure, such as statements and branches. Grey-box combines both, for example testing through the UI while also checking the database or logs.

Question 25

What are the levels of testing?

Accepted Answer

The four levels are unit testing of individual components, integration testing of interactions between components, system testing of the complete application against requirements, and acceptance testing by users or the business to confirm it is fit for use.

Question 26

What is the difference between alpha and beta testing?

Accepted Answer

Alpha testing is done by internal staff or a selected group at the developer's site before release, often in a controlled environment. Beta testing is done by real users in their own environment on a near-final version to get real-world feedback.

Question 27

What is the difference between an error, defect, bug and failure?

Accepted Answer

An error is a human mistake, such as a developer misunderstanding a requirement. That mistake introduces a defect, commonly called a bug, in the code or document. A failure is when the defect is executed and the system behaves differently from what is expected.

Question 28

What should a good bug report contain?

Accepted Answer

A good bug report has a clear title, environment and build version, preconditions, numbered steps to reproduce, test data, expected versus actual result, severity and priority, and evidence like screenshots, videos or logs.

Question 29

What is the difference between static and dynamic testing?

Accepted Answer

Static testing examines work products without executing code, through reviews, walkthroughs, inspections and static analysis of requirements, designs or code. Dynamic testing executes the software and compares actual behaviour with expected results.

Question 30

What is the difference between positive and negative testing?

Accepted Answer

Positive testing uses valid inputs to confirm the system works as expected, while negative testing uses invalid or unexpected inputs to confirm it handles them gracefully with proper error messages and no crashes.

Question 31

Scenario: how would you test a pen?

Accepted Answer

I would first ask clarifying questions: what type of pen, who the users are and what requirements exist. Then I would cover functional tests like writing smoothly and ink flow, physical tests like grip, cap fit and dimensions, durability tests like drops and ink lifetime, and safety tests such as non-toxic ink and choke-safe caps.

Question 32

What is a Requirement Traceability Matrix (RTM)?

Accepted Answer

An RTM is a document that maps each requirement to its test cases, and often to execution results and defects. It ensures every requirement is covered by tests and helps assess impact when a requirement changes.

Question 33

What are entry and exit criteria?

Accepted Answer

Entry criteria are conditions that must be met before a test phase starts, such as a stable build, test environment ready and test cases reviewed. Exit criteria define when the phase can end, such as all planned tests executed, a target pass rate met and no open critical or high defects.

Question 34

What is the difference between a test plan and a test strategy?

Accepted Answer

A test strategy is a high-level, usually organisation- or programme-level document describing the overall testing approach, levels, types, tools and standards. A test plan is project or release specific and details scope, schedule, resources, environments, risks and entry and exit criteria.

Question 35

What is state transition testing? Give an example.

Accepted Answer

State transition testing models a system as states, events and transitions, and designs tests to cover valid and invalid transitions. A classic example is login lockout: after three wrong passwords the account moves from Active to Locked, and a correct password should then not log the user in.

Question 36

What are error guessing and use case testing?

Accepted Answer

Error guessing uses the tester's experience to predict where bugs are likely, such as empty fields, special characters, leap years or double clicks. Use case testing derives tests from user-system interactions, covering the main flow, alternate flows and exception flows end to end.

Question 37

Scenario: how would you test a login page?

Accepted Answer

I cover functional cases like valid login, invalid username or password, empty fields, case sensitivity and remember-me, plus security cases like password masking, account lockout, SQL injection, HTTPS and session handling. I also check UI and usability, accessibility, browser and device compatibility, and performance under many logins.

Question 38

What is defect triage, and what do Deferred, Rejected and Duplicate mean?

Accepted Answer

Defect triage is a regular meeting where QA, dev and product review new defects to confirm validity, set severity and priority, and assign owners. Rejected means it is not a bug, Duplicate means it is already reported, and Deferred means it is valid but postponed to a future release.

Question 39

What is the difference between usability and accessibility testing?

Accepted Answer

Usability testing checks how easy and intuitive the product is for typical users to achieve their goals. Accessibility testing checks that people with disabilities can use it, for example with screen readers, keyboard-only navigation or low vision, usually against WCAG guidelines.

Question 40

How do you estimate testing effort?

Accepted Answer

I break the work into tasks such as analysis, test design, data and environment setup, execution, regression and reporting, then estimate each using past data or three-point estimation. I add buffer for defect retesting and risk, and in Agile I contribute testing effort to story points.

Question 41

What is the difference between ad-hoc, monkey and exploratory testing?

Accepted Answer

Ad-hoc testing is informal, unplanned testing based on the tester's knowledge with no documentation. Monkey testing feeds random inputs without any knowledge of the system to see if it crashes. Exploratory testing is structured learning, design and execution at the same time, usually guided by a charter and time-box.

Question 42

What is shift-left testing?

Accepted Answer

Shift-left means involving testing earlier in the lifecycle: reviewing requirements, defining acceptance criteria with the team, testing APIs before the UI is ready, and running automated checks on every commit. It finds defects when they are cheapest to fix.

Question 43

What is pairwise (all-pairs) testing and when would you use it?

Accepted Answer

Pairwise testing is a combinatorial technique that covers every pair of parameter values at least once instead of every full combination, based on the observation that most defects are triggered by one or two interacting factors. I use it for configuration-heavy features like browser, OS, language and payment method combinations.

Question 44

Scenario: how would you test an ATM?

Accepted Answer

I split it into card and PIN validation, transactions like withdrawal, balance enquiry and transfer, cash dispensing, receipts, and hardware and network failures. The critical cases are around money: insufficient balance, daily limits, exact denominations, and what happens if power or network fails after the account is debited but before cash is dispensed.

Question 45

Scenario: a developer says your bug is 'not a bug'. What do you do?

Accepted Answer

I first re-check the requirement and reproduce the issue, then discuss it with the developer using evidence: the acceptance criteria, screenshots, logs and user impact. If we still disagree, the product owner or BA decides, since it is a question of expected behaviour, and we document the outcome.

Question 46

Scenario: you have too little time to test before release. What do you do?

Accepted Answer

I prioritise by risk: critical business flows, recently changed areas and historically buggy modules first, with a smoke and targeted regression instead of the full suite. I communicate clearly what was tested and what was not, so stakeholders make an informed go/no-go decision.

Question 47

Scenario: how would you test an e-commerce checkout and payment flow?

Accepted Answer

I test cart totals with tax, shipping, discounts and coupons, address and delivery options, and every payment method with success, decline, timeout and cancellation. The key risks are double charging, orders created without payment, and stock or price changes during checkout, so I also verify the order, payment and inventory records match.

Question 48

How do you select and prioritise tests for a regression cycle?

Accepted Answer

I combine impact analysis of what changed with risk: core business flows and high-usage features always, areas touched by the change and their dependencies, and modules with a history of defects. Tests are tiered into smoke, high, medium and low priority, and the suite is pruned regularly to remove obsolete or duplicate cases.

Question 49

Which QA metrics do you track, such as defect leakage and DRE?

Accepted Answer

I track test execution progress and pass rate, requirement coverage, defect density, defect leakage and Defect Removal Efficiency. DRE is defects found before release divided by total defects including those found after release, times 100, and leakage is the inverse view: the share that escaped to production.

Question 50

Scenario: requirements change in the middle of a sprint. How do you handle testing?

Accepted Answer

I raise it with the product owner and team so the change is visible and the scope is renegotiated, then do impact analysis on existing test cases, update or add tests and the RTM, and re-estimate. If the change is large, it should become a new story rather than silently expanding the current one.

Interview Questions

01What is the difference between SDLC and STLC?BeginnerBasics

02What is the difference between verification and validation?BeginnerBasics

03What is the difference between severity and priority? Give examples.BeginnerDefect Management

04Explain the bug life cycle.BeginnerDefect Management

05What is the difference between smoke and sanity testing?BeginnerTesting Types

06What is the difference between retesting and regression testing?BeginnerTesting Types

07What is the difference between functional and non-functional testing?BeginnerTesting Types

08Explain Boundary Value Analysis with an example.IntermediateTest Design Techniques

09What is Equivalence Partitioning?IntermediateTest Design Techniques

10When would you use decision table testing?IntermediateTest Design Techniques

11What does a test plan contain?IntermediateTest Planning & Process

12What makes a good test case?IntermediateTest Planning & Process

13What is the role of QA in an Agile Scrum team?IntermediateAgile & Collaboration

14What is exploratory testing and when is it useful?IntermediateTesting Types

15What is UAT and who performs it?IntermediateTesting Types