Latest Questions 84 total
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1What is the difference between a product company and a service company for developers?
**Service Company (IT Services / Outsourcing):**
TCS, Infosys, Wipro, HCL, Cognizant
- You work on clients' projects
- Technology stack deci...
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2How to answer 'Tell me about yourself' in a tech interview?
This is always the first question — most candidates waste it. Here's the formula:
**Structure: Present → Past → Future**
*Present:* ...
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3What is the difference between OpenAI GPT-4o and GPT-4o-mini?
Both are OpenAI models but optimised for different use cases:
| Feature | GPT-4o | GPT-4o-mini |
|---|---|---|
| Intelligence | Highest | G...
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4What are LangChain agents and how do they differ from chains?
**LangChain Chains:**
- Fixed, predefined sequence of steps
- The flow is hardcoded by the developer
- Deterministic — same input → same...
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5What is a vector database and why is it used in AI applications?
A vector database stores data as high-dimensional vectors (embeddings) and enables fast similarity search.
**Why it's needed:**
LLMs unders...
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6How does garbage collection work in Python?
Python uses two mechanisms for memory management:
**1. Reference Counting (primary):**
Every object has a reference count. When it reaches ...
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7What are Python generators and when should you use them?
A generator is a function that yields values one at a time instead of returning them all at once — saving memory.
**Regular function vs G...
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8What is the difference between multiprocessing and multithreading in Python?
Due to Python's GIL (Global Interpreter Lock), threads can't run Python code in parallel — only one thread executes at a time.
**Multithr...
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9How to prepare for a Java developer interview?
Java interviews at product companies cover 4 areas. Here's exactly what to prepare:
**1. Core Java (always asked):**
- OOPs: inheritance, p...
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10What skills are needed to become a DevOps engineer in 2025?
DevOps engineer is one of the highest-paying roles in tech. Here's the complete skill map:
**Foundation (must-have):**
- Linux command line...
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11What is the salary of a full stack developer in India 2025?
Full stack developer salaries in India (2025):
**By experience:**
- Fresher (0-1 year): ₹3.5 – ₹7 LPA
- Junior (1-3 years): ₹7 – ...
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12What is MongoDB aggregation pipeline?
The aggregation pipeline processes documents through a sequence of stages, similar to SQL's GROUP BY + JOINs.
**Common stages:**
- `` — f...
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13How do you handle authentication in a MERN stack app?
The standard approach uses JWT (JSON Web Tokens):
**Flow:**
1. User logs in → sends email + password to Express
2. Express validates cred...
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14What is the difference between useCallback and useMemo in React?
Both are React hooks for performance optimisation — they prevent unnecessary recalculations:
**useMemo — memoises a VALUE:**
```jsx
con...
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15What is the MERN stack and how does it work together?
MERN is a full-stack JavaScript framework combining 4 technologies:
**M — MongoDB:** NoSQL database (stores data as JSON documents)
**E �...
