Question library
Explained questions for the decisions developers make.
What does an ORM do underneath?
An ORM translates object-oriented data operations into database commands and maps results back into application objects. It reduces repetitive persistence code, but the database still executes real SQL with real locks, indexes and query costs. Understanding the generated query is essential when debugging correctness or performance.
Monolith vs modular monolith vs microservices?
A monolith is deployed as one application, a modular monolith keeps clear internal feature boundaries within that deployment, and microservices are independently deployable services. These choices affect how teams change code, scale workloads and handle failure. Microservices reduce some coupling but introduce network calls, distributed data and operational coordination.
XSS vs CSRF vs CORS?
XSS, CSRF and CORS concern browser trust but refer to different mechanisms. XSS runs attacker-controlled script in a trusted page, CSRF triggers requests with automatically attached credentials, and CORS controls whether browser code may read cross-origin responses. A defense for one does not automatically solve the others.
How do DNS, load balancers, IAM and secrets fit together?
DNS resolves names to records, load balancers select healthy destinations, IAM controls identities and permissions, and secret managers store sensitive credentials. These components connect an application to users and dependencies without putting all configuration into code. A failure at any layer can look like “the API is down” from the outside.
A cloud API is unreachable. Where do I start?
An unreachable cloud API may fail before the request reaches application code. DNS, TLS, routing, firewall rules, load-balancer health and listening ports are separate layers to verify. Checking them in order avoids opening broad access or restarting healthy services without evidence.
What performance issue did you face?
A performance story starts with a measured symptom and the workload that exposed it. It should explain how you separated potential causes and what work the final change reduced. A faster-looking code snippet is not a complete result without checking the same behavior and load.
How do I explain stored procedure optimization?
A stored procedure is database-side code that groups SQL operations and control flow into a callable unit. It can reduce application round trips and centralize data logic, but a procedure can still contain slow queries or hold locks too long. Optimization begins by finding the expensive statements and understanding their plans and transaction behavior.
How do I spot common React and async bugs?
React and async bugs often come from incorrect assumptions about identity, snapshots and completion order. A render's values can be captured by a callback, and asynchronous results may arrive after the UI has moved on. Review the lifecycle and timeline rather than checking syntax alone.
How do you remove duplicate IDs from an array?
Deduplication removes repeated values according to a defined equality rule. JavaScript Set handles primitive IDs conveniently and keeps the order of first insertion. Objects are compared by reference, so deduplicating records by an id field requires an explicit key-based approach.
AI, machine learning, deep learning, and generative AI
Artificial intelligence, or AI, is the broad field of making software perform tasks such as recognizing speech, finding patterns, or understanding language. Machine learning, or ML, learns patterns from examples instead of requiring a rule for every case.…
Function calling and tool calling
Function calling lets a model propose a named function and structured arguments. Tool calling is the broader pattern that includes functions and capabilities such as search or code execution. A proposed tool call is an untrusted request that your application…
Virtual environments, pip, and project structure
A virtual environment isolates a project's Python packages. pip installs packages into the selected environment. Project structure separates API routes, business services, adapters, and tests so the AI code does not become one notebook-sized script.
Basic NumPy, Pandas, and Jupyter
NumPy provides efficient numerical arrays and vector operations. Pandas provides table-like data structures for cleaning and analyzing datasets. Jupyter provides interactive notebooks that mix code, results, and explanations.
Interrupts and human review
An interrupt pauses graph execution and exposes a payload for external input. Resumption supplies the requested value. The node containing the interrupt can run again from its beginning on resume, so code before the pause may repeat.
Choosing orchestration tools
Workflow engines and job systems provide different guarantees for dispatch, persistence, recovery, waiting, and coordination. Temporal is a durable workflow platform; BullMQ is a Redis-backed job library; Inngest and Trigger.dev offer developer-oriented…
MCP architecture: host, client, and server
MCP is a protocol for connecting AI applications to external tools and context. The host is the application using the model; a client is its protocol connection to a server; a server exposes supported capabilities. The model normally proposes operations,…
Azure AI Search, Functions, Container Apps, Key Vault, and Entra ID
Azure AI Search provides searchable indexes and retrieval capabilities. Functions runs event-driven code; Container Apps runs containerized services/jobs. Key Vault manages secrets/keys, while Entra ID provides identity capabilities and access integration.
Embeddings
Beginner — Explain an embedding.
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