Solved: Going to my first ever Technical Interview tomorrow! What do I need to know?

🚀 Executive Summary

TL;DR: First-time technical interviewees often face pre-interview jitters and analysis paralysis, focusing on memorizing obscure commands. The solution involves mastering fundamental Linux/Unix and networking concepts, structuring problem-solving with a ‘Clarify, Propose, Justify’ framework, and preparing for real-world system design and behavioral scenarios to demonstrate critical thinking and communication.

🎯 Key Takeaways

• Master Linux/Unix core concepts like file permissions (e.g., chmod 755), processes (ps, top), and I/O redirection (|, >), explaining the *why* behind commands.
• Understand networking essentials including TCP vs. UDP trade-offs, the high-level DNS lifecycle, and common ports (22, 80, 443, 53) with practical application (e.g., curl -v).
• Adopt the ‘Clarify, Propose, Justify’ framework for troubleshooting and system design questions, demonstrating a methodical, data-driven approach to problem-solving.

Ace your first technical interview with this senior DevOps engineer’s guide for IT professionals. Learn how to master fundamentals, structure your problem-solving, and tackle real-world system design and troubleshooting scenarios with confidence.

Symptoms: The Pre-Interview Jitters

You’ve landed your first technical interview. The initial excitement has been replaced by a growing sense of dread. Your browser history is a chaotic mix of “top 100 Kubernetes questions,” “Linux command line cheat sheets,” and “how to reverse a binary tree on a whiteboard.” You’re experiencing a classic case of pre-interview analysis paralysis. The core symptoms include:

• A frantic urge to memorize command-line flags for tools you’ve only used a few times.
• The fear of a single “gotcha” question derailing the entire conversation.
• Impostor syndrome telling you that you don’t know enough, and they’re about to find out.
• Uncertainty about how to approach an open-ended problem you’ve never seen before.

The good news is that every senior engineer has been in your shoes. The goal of a good technical interview isn’t to test your ability to recall obscure syntax; it’s to evaluate how you think, solve problems, and communicate. Here are three practical, actionable solutions to help you demonstrate your skills effectively.

Solution 1: Master the Fundamentals, Not Just the Buzzwords

Tools like Terraform, Docker, and Jenkins are essential, but they are abstractions built on top of fundamental principles. An interviewer is more interested in your understanding of *why* these tools exist than your memorization of their every command. Focus your final hours of preparation on reinforcing these core concepts.

Linux/Unix Core Concepts

The command line is your primary interface to the infrastructure. Show you’re comfortable there. You don’t need to be a kernel developer, but you should be able to navigate the system and understand its core tenets.

• File Permissions: Understand what read, write, and execute mean for files and directories. Be prepared to explain what a common permission set like 755 means.
• Processes: Know how to list running processes (ps), check resource usage (top, htop), and understand the difference between a running process and a background service.
• I/O Redirection: Explain the difference between standard output (stdout) and standard error (stderr) and how to use pipes (|) and redirects (>, 2>&1).

For example, if asked about setting script permissions, don’t just state the command. Explain it.

chmod 755 my_script.sh

“I’d use chmod 755. This grants the owner read, write, and execute permissions (4+2+1=7), while the group and others get read and execute permissions (4+0+1=5). This is a common setting for executable scripts, ensuring the owner can modify it while others can only run it.”

Networking Essentials

You can’t manage infrastructure without understanding how machines talk to each other. Focus on the practical application.

• TCP vs. UDP: Know the difference. TCP is connection-oriented and reliable (e.g., HTTP), while UDP is connectionless and fast (e.g., DNS, video streaming). Understand the trade-offs.
• The DNS Lifecycle: Be able to walk through what happens when you type google.com into a browser at a high level. Your browser checks its cache, then the OS cache, then asks the configured resolver, which then queries root servers, TLD servers, and finally the authoritative nameserver.
• Common Ports: You should know what runs on ports 22 (SSH), 80 (HTTP), 443 (HTTPS), and 53 (DNS) without hesitation.

A simple command can demonstrate this knowledge:

curl -v https://api.example.com

“To check connectivity to an API endpoint, I’d start with curl -v. The verbose flag shows me the DNS resolution, the TCP handshake, the TLS negotiation, and the HTTP request and response headers. This can quickly tell me if the problem is at the DNS, network, or application layer.”

Solution 2: Structure Your Problem-Solving Approach

When you’re faced with a troubleshooting or design question, the worst thing you can do is jump to a single conclusion or start coding silently. Interviewers want to see your thought process. Use a structured approach to talk through the problem.

The “Clarify, Propose, Justify” Framework

Instead of rambling, break your answer down into logical steps. Let’s use a classic scenario.

The Scenario: “A customer is reporting that our website is slow. How would you investigate?”

1. Clarify (Ask Questions First): Resist the urge to start listing tools. Gather requirements to narrow the scope.
   • “Is it slow for all users or just this one? Geographically isolated?”
   • “When did this start? Does it correlate with a recent deployment?”
   • “Is the entire site slow, or just a specific page or action, like submitting a form?”
   • “What is our definition of ‘slow’? Do we have SLOs or metrics to compare against?”
2. Propose (Form a Hypothesis): Based on the (hypothetical) answers, state where you would start looking.

“Assuming it’s a widespread issue affecting the entire site that started an hour ago, my initial hypothesis would be a bottleneck in a shared resource. I would start my investigation from the outside in, beginning with our monitoring and observability platforms.”

1. Justify (Explain Your Plan): Detail the steps you would take and, critically, *why* you are taking them. This demonstrates experience.
   • “First, I’d check our APM tool, like Datadog or New Relic, to look for increased application latency (p95, p99), error rates, or slow database query transactions. This gives the broadest view.”
   • “If the APM shows high latency in database calls, I’d move to the database server. I’d use htop to check for CPU or memory pressure and check the database’s slow query log.”
   • “If the APM looks normal, I would check infrastructure metrics on the web servers: CPU utilization, memory, and network I/O. A sudden spike could indicate a resource exhaustion issue.”
   • “If all that looks normal, I’d investigate upstream dependencies, like third-party APIs or a CDN, to see if they are experiencing an incident.”

This approach shows you are methodical, data-driven, and consider the entire system rather than just one component.

Solution 3: Prepare for “Real World” Scenarios

Beyond specific commands, interviewers want to gauge your architectural sense and your ability to work on a team. This often comes in the form of system design questions and behavioral questions.

System Design Questions

You might hear: “Design a simple, scalable architecture for a blog.” Again, the goal is to see how you think. A junior candidate gives a simple answer. A senior candidate explores the trade-offs.

Vague, Tool-Focused Answer	Structured, Concept-Focused Answer
“I’d use an EC2 instance with Apache, MySQL, and WordPress on it. Maybe use an S3 bucket for images.”	“I’d start by clarifying requirements like expected traffic and availability. For a scalable solution, I’d propose a multi-tier architecture: * Load Balancer: An AWS ALB to distribute traffic across web servers and handle SSL termination. * Web Tier: An Auto Scaling Group of EC2 instances running Nginx. This allows us to scale horizontally based on traffic. * Database Tier: A managed database service like AWS RDS for MySQL. This handles backups, patching, and failover, improving reliability. * Caching: A caching layer like Redis or Memcached for database queries and user sessions to reduce load on the database. * Static Assets: Use a CDN like CloudFront pointing to an S3 bucket for images and CSS to improve global load times and reduce server load. This design separates concerns and allows each tier to be scaled independently.”

Behavioral Questions: The Post-Mortem Mindset

When you’re asked, “Tell me about a time you made a mistake” or “Tell me about a production outage you were involved in,” they are testing for ownership, maturity, and a blameless culture mindset.

The best way to answer is to structure it like a post-mortem:

• Situation: Briefly describe the context and your role.
• The Incident: State clearly what happened and what the impact was. Be honest. “I ran a database migration script without running it in a dry-run mode first, which caused a 15-minute outage for our primary API.”
• The Fix: Explain the immediate steps you took to mitigate and resolve the issue. “We immediately rolled back the change and restored the database from a recent snapshot.”
• The Root Cause: Explain what the underlying problem was. “The root cause was not a technical failure but a process failure. Our deployment process did not mandate a dry-run or a peer review for this type of change.”
• The Follow-up: This is the most important part. What did you and the team do to prevent this class of problem from happening again? “We updated our CI/CD pipeline to automatically enforce a dry-run for all database migrations and updated our team’s checklist to require a peer review before deployment.”

This answer shows you don’t blame others, you take ownership, and you are focused on improving the system and process as a whole. That’s the mark of a great engineer.

---

👉 Read the original article on TechResolve.blog

---

☕ Support my work

If this article helped you, you can buy me a coffee:

👉 https://buymeacoffee.com/darianvance