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2027 Interview Question Bank • Page 4 of 4

Production Codebase Audits: Full-Stack Errors, Security, SEO/GEO & Scaling (30 Q&As + Code)

Hardcoded secret leaks, SSRF cloud metadata defense, reflected XSS & CSP, concurrency quota locks, SQLi in MCP tools, Technical SEO/GEO crawlability (robots/noindex/SSR/JSON-LD/llms.txt), CLS, and OOM/N+1 scaling.

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Q91CoreAsked at: Bloomberg · Google · AccentureFree Sample

You inspect a Node server.js containing process.env.OPENAI_API_KEY || "sk-live-..." and an unauthenticated /api/debug-env endpoint. Why is this an instant P0 fail and how do you fix it?

Committed fallback credentials remain readable to anyone cloning the repo, and /api/debug-env leaks live database passwords and API secrets over HTTP. Delete debug routes immediately, scrub git history / rotate compromised keys, fail fast on startup if required secret env vars are absent, and load credentials cleanly from IAM/Secrets Manager.

Production Pattern
// BAD: secret fallback + public leak
const key = process.env.OPENAI_API_KEY || "sk-live-HARDCODED";
// GOOD: fail-fast startup + zero debug exposure
const key = process.env.OPENAI_API_KEY;
if (!key) throw new Error("Missing required OPENAI_API_KEY");
Interviewer Rejection Signal: Leaving fallback secrets in repo code or gating /api/debug-env behind a weak URL query password.
Q92SeniorAsked at: Google · DeepMind · CapgeminiFree Sample

Audit a storefront where robots.txt has Disallow: /, HTML uses <meta name="robots" content="noindex, nofollow">, and products render strictly via client fetch(). Why do Google AND AI search bots ignore it?

Googlebot and Bingbot stop immediately at Disallow: / and noindex. Furthermore, many AI answer/GEO crawlers do NOT run heavy client JavaScript bundles—meaning an empty <div id="catalog-root"></div> shows zero products! Fix by permitting crawling, using index, follow, server-rendering catalog HTML + <link rel="canonical"> + JSON-LD Product schema + llms.txt.

Production Pattern
# robots.txt
User-agent: *
Allow: /
Sitemap: https://example.com/sitemap.xml
# HTML: remove noindex, serve SSR catalog items + <script type="application/ld+json">
Interviewer Rejection Signal: Assuming Google/AI crawlers index client-only JS SPAs cleanly despite Disallow: / or noindex.
Q93StaffAsked at: Amazon · Bloomberg · Stripe

How do attackers exploit an unvalidated /api/preview?url=... link-preview endpoint (SSRF) in AWS/GCP/Azure—and how do you patch it thoroughly?

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Q94CoreAsked at: Bloomberg · Meta · TCS

Why does statusEl.innerHTML = "Showing: " + userQuery create Reflected XSS—and why is .textContent vastly safer than regex stripping <script>?

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Q95SeniorAsked at: OpenAI · Anthropic · Infosys

In Python quota_limiter.py, if current + tokens <= 1000: time.sleep(0.02); usage[t] = current + tokens leaks quota under 4 concurrent requests. Fix it both locally and for distributed Kubernetes pods.

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Q96SeniorAsked at: Anthropic · EY · Scale AI

An MCP tool executes cursor.execute(f"SELECT * FROM tickets WHERE id = '{ticket_id}'"). Why is this catastrophic when combined with Indirect Prompt Injection?

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Q97CoreAsked at: DeepMind · Bloomberg · Google

A storefront dynamically injects a promo banner above the catalog after 600ms, jumping buttons downward under the user’s mouse. Name the Core Web Vital violated and exact CSS fix.

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Q98CoreAsked at: Amazon · Wipro · Accenture

An Express/Node endpoint appends every incoming AI prompt into const logs = [] in module scope and scans reviews in a nested for loop. What two production crashes occur?

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Q99SeniorAsked at: Snowflake · Cognizant · Microsoft

Why does returning confidential HR documents inside an API response and hiding them inside browser React JS violate RBAC security completely?

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Q100SeniorAsked at: Bloomberg · Google

What belongs in an LLM-friendly llms.txt + JSON-LD setup for 2027 GEO (Generative Engine Optimization)?

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Q101CoreAsked at: TCS · Wipro

Why do raw 500 error stack traces (res.end(err.stack)) in production HTTP handlers hurt security?

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Q102SeniorAsked at: AWS · OpenAI

How do you protect an expensive /api/ai-summary route against bot credential stuffing and burst wallet drain?

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Q103CoreAsked at: Google · Accenture

Inspecting CSS, you find light gray #cbd5e1 status text rendered on near-white #f8fafc background. What accessibility rule breaks and how do you verify it?

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Q104SeniorAsked at: Stripe · JPMC

What is BOLA / IDOR (Broken Object Level Authorization) inside an AI document chat API like GET /api/chats/:chatId?

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Q105CoreAsked at: Google · Meta

Why must multi-parameter filtered URLs (like /products?sort=price&page=2) set a clean <link rel="canonical"> tag?

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Q106SeniorAsked at: Anthropic · EY

Walk through the top 3 OWASP Top 10 for LLM Applications vulnerabilities (LLM01, LLM02, LLM06) with concrete fixes.

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Q107CoreAsked at: Bloomberg · AWS

What HTTP security headers protect a modern AI web frontend from clickjacking, MIME sniffing, and inline script XSS?

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Q108SeniorAsked at: Google · OpenAI

Why do synchronous fs.readFileSync or massive JSON.parse loops inside Node.js HTTP handlers destroy P99 latency for ALL users?

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Q109SeniorAsked at: Accenture · Cognizant

Before storing prompts into third-party observability (Langfuse/Datadog), how do you strip customer Aadhaar, PAN, SSN, and emails reliably?

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Q110CoreAsked at: Google · Vercel

Compare CSR vs SSR vs SSG vs ISR in Next.js when shipping thousands of AI documentation & interview pages for Google & AdSense.

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Q111SeniorAsked at: Meta · Cloudflare

How do you prevent Regex Denial of Service (ReDoS) when validating complex AI prompts or URL inputs in Node/Python?

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Q112CoreAsked at: Stripe · Amazon

What goes wrong when an AI streaming endpoint shares one unisolated upstream HTTP pool without Circuit Breakers and Timeouts?

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Q113SeniorAsked at: Google · Wipro

Why must sitemap.xml dynamically stay synchronized cleanly with your canonical routes—and omit noindex or broken paths?

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Q114CoreAsked at: Anthropic · GitHub

An AI coding assistant wants permission to inspect a local project workspace. What filesystem & command sandbox rules prevent accidental rm -rf or .env theft?

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Q115SeniorAsked at: OpenAI · Scale AI

What is "Markdown / Image Exfiltration" in AI Chat UIs—and how does a single unsafe <img> link steal private RAG docs?

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Q116CoreAsked at: Google · Bloomberg

How does semantic HTML (<main>, <article>, <h1>..<h3> hierarchy, <nav>) impact BOTH screen readers and 2027 AI Search (GEO) citation extraction?

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Q117SeniorAsked at: Databricks · Deloitte

Why are File Uploads (PDFs/CSVs/Images) entering a RAG ingestion pipeline a classic security hazard if parsed naively?

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Q118CoreAsked at: TCS · Morgan Stanley

Explain why Cache-Control: public, max-age=3600 on an authenticated /api/user/profile or /api/rag-chat route causes data leaks.

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Q119SeniorAsked at: Google · Stripe

What causes INP (Interaction to Next Paint) sluggishness in data-heavy AI coding/interview web apps—and how do you keep INP under 200ms?

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Q120StaffAsked at: OpenAI · Google · Amazon

During a full-stack codebase interview audit, what 5-minute triage checklist catches 90% of critical defects immediately?

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