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DevOps Telephonic Interview Questions & Answers

30 questions for the telephonic interview stage — 17 easy, 12 medium, 1 hard.

About the telephonic interview round

The telephonic or screening round is a 15-30 minute call with a recruiter or engineer. It checks your basics, your CV and whether you can explain DevOps concepts clearly without a screen to point at.

Tips for the telephonic interview round

  • Keep your CV in front of you and be ready to explain every line on it.
  • Answer in short, clear sentences; there is no whiteboard, so structure matters.
  • Take the call somewhere quiet and confirm the time in advance.
  • Prepare one question to ask the interviewer at the end.
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01

What is the difference between a Pod, a ReplicaSet and a Deployment?

KubernetesEasy
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A Pod is the smallest deployable unit: one or more containers sharing network and storage. A ReplicaSet keeps a specified number of identical pods running. A Deployment manages ReplicaSets and adds rolling updates and rollbacks by creating a new ReplicaSet for each version. In practice you create Deployments and rarely touch ReplicaSets or bare pods directly.
02

The build works on your laptop but fails on the CI server. How do you debug it?

CI/CD PipelinesEasy
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The environments differ. Compare tool versions such as JDK, Node or Python, environment variables, and dependency versions, especially if there is no lock file. Check for files present locally but not committed, and for hard-coded paths. Reproduce by running the build inside the same Docker image the CI agent uses. Long term, build inside containers so local and CI match.
03

Explain the basic Terraform workflow.

Infrastructure as Code (Terraform and Ansible)Easy
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terraform init downloads providers and modules and configures the backend. terraform fmt and validate check style and syntax. terraform plan shows what will be created, changed or destroyed without making changes. terraform apply executes the plan after confirmation. terraform destroy removes all managed resources. In CI, save the plan with -out and apply that exact plan after review.
04

You suddenly cannot SSH into a Linux server. What do you check?

Linux and Shell ScriptingMedium
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Check reachability with ping and whether port 22 is open with nc -zv host 22. Then look at security groups, firewall rules and whether the sshd service is running, using the cloud console or serial access. Run ssh -vvv to see whether it fails at key exchange or authentication. Common causes are wrong key permissions, a full disk, a changed IP, or fail2ban blocking you.
05

What does git cherry-pick do?

Git and Version ControlEasy
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git cherry-pick <hash> applies the changes of one specific commit onto your current branch as a new commit. It is useful to bring a hotfix from main into a release branch without merging everything else. Overusing it creates duplicate commits with different hashes and can cause confusing conflicts later, so prefer merging when you need a whole set of changes.
06

What is git stash and when do you use it?

Git and Version ControlEasy
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git stash saves your uncommitted changes and cleans the working directory, so you can switch branches for an urgent fix. git stash list shows saved entries, git stash pop reapplies the latest and removes it, and git stash apply keeps it. Use git stash -u to include untracked files. It is a short-term tool; for longer work, commit on a branch.
07

What is a DaemonSet and when is it used?

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A DaemonSet makes sure one copy of a pod runs on every node, or on a selected group of nodes. When a node joins the cluster, the pod is added automatically. It is used for node-level agents such as log collectors like Fluent Bit, monitoring agents like the Prometheus node exporter, and CNI or storage plugins.
08

An EC2 instance in a private subnet cannot download packages from the internet. Why?

AWS Cloud for DevOpsMedium
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A private subnet has no direct route to the Internet Gateway. Check that its route table sends 0.0.0.0/0 to a NAT Gateway placed in a public subnet, that the NAT Gateway has an Elastic IP, and that the security group and NACL allow outbound traffic and return ports. For AWS services like S3, a VPC endpoint avoids NAT data charges.
09

What is the difference between a Docker image and a container?

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An image is a read-only template made of layers, containing the application, libraries and configuration, built from a Dockerfile. A container is a running instance of an image with a thin writable layer on top. You can start many containers from one image. Changes made inside a container are lost when it is removed unless they are stored in volumes.
10

Explain Ansible architecture: inventory, modules and playbooks.

Infrastructure as Code (Terraform and Ansible)Easy
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Ansible runs from a control node and connects to managed hosts over SSH, or WinRM for Windows, with no agent needed. The inventory lists hosts and groups. Modules are units of work like apt, copy or service. Playbooks are YAML files containing plays that map host groups to ordered tasks. Variables, templates with Jinja2 and roles organise larger automation.
11

What is the difference between kill, kill -15 and kill -9?

Linux and Shell ScriptingEasy
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kill sends SIGTERM (15) by default, which asks the process to stop so it can close files, finish requests and clean up. kill -9 sends SIGKILL, which the kernel enforces immediately; the process cannot catch it, so data may be lost and temp files left behind. Always try SIGTERM first and use SIGKILL only when the process does not respond.
12

Builds fail randomly because of flaky tests. How do you handle it?

CI/CD PipelinesMedium
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First identify flaky tests by tracking which tests fail and pass on the same commit. Quarantine them into a separate non-blocking job so the main pipeline stays trustworthy, and raise tickets with owners. Common causes are timing assumptions, shared test data, order dependence and external services. Blind automatic retries hide real bugs, so use them only briefly while fixing the root cause.
13

What is the Terraform state file and why is it important?

Infrastructure as Code (Terraform and Ansible)Medium
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terraform.tfstate maps the resources in your code to real resources in the cloud, storing their IDs and attributes. Terraform compares code, state and reality to decide what to create, change or destroy. Without it Terraform would not know what it manages. It may contain secrets in plain text, so store it in a secure remote backend, never in Git.
14

What is the AWS shared responsibility model?

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AWS is responsible for security of the cloud: physical data centres, hardware, the network and the hypervisor. The customer is responsible for security in the cloud: IAM, data encryption, OS patching on EC2, security groups and application code. The split shifts with the service; for managed services like RDS or Lambda, AWS handles more of the underlying patching.
15

Explain the Jenkins controller and agent architecture.

CI/CD PipelinesMedium
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The Jenkins controller stores configuration, schedules jobs, serves the UI and keeps build history. Agents are separate machines or containers that actually execute build steps, connected over SSH or JNLP and selected by labels. Running builds on agents rather than the controller keeps the controller stable and secure, and lets you scale with dynamic agents on Kubernetes or cloud VMs that are created per build.
16

What is the difference between a security group and a network ACL?

AWS Cloud for DevOpsMedium
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A security group acts as a firewall for instances or network interfaces. It is stateful, so return traffic is allowed automatically, and it supports only allow rules. A network ACL works at the subnet level, is stateless, so inbound and outbound rules must both allow traffic, supports allow and deny rules, and evaluates rules in number order. Security groups are the main control.
17

Explain Linux file permissions and what chmod 755 means.

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Every file has read (4), write (2) and execute (1) bits for three classes: owner, group and others. chmod 755 gives the owner 7 (read, write, execute) and gives group and others 5 (read, execute). It is typical for scripts and directories that everyone may run or enter but only the owner may change. Use ls -l to see permissions.
18

What is Site Reliability Engineering, and what is toil?

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SRE, which began at a large search company, applies software engineering to operations: teams own reliability through SLOs, error budgets, automation, incident management and capacity planning. Toil is manual, repetitive, automatable work that grows with scale and adds no lasting value, such as manually restarting services. SRE teams aim to keep toil below about half their time and automate the rest.
19

What is the difference between a process and a thread in Linux?

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A process is a running program with its own address space, file descriptors and PID. A thread is a unit of execution inside a process that shares the same memory and open files with other threads. Creating threads is cheaper and they communicate easily, but a bug in one thread can crash the whole process, while separate processes are isolated from each other.
20

What is the difference between continuous integration, continuous delivery and continuous deployment?

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Continuous integration means developers merge small changes often and every merge is automatically built and tested. Continuous delivery goes further: every passing build is packaged and ready to release, but a human approves the production push. Continuous deployment removes that manual step, so every change that passes all checks goes to production automatically. Each stage needs more test confidence than the last.
21

You need one pipeline that deploys to dev, staging and production with approval before production. How do you design it?

CI/CD PipelinesMedium
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Build and test once, publish a versioned artefact, then promote it through environments. Dev deploys automatically on merge, staging deploys after dev smoke tests, and production waits for a manual approval from authorised people using a Jenkins input step or GitHub environment protection rules. Keep environment-specific settings in config files or parameters, not separate pipelines, and record who approved each release.
22

What is Docker Compose?

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Docker Compose defines and runs multi-container applications from a YAML file, usually compose.yaml. You describe services, networks, volumes, environment variables and dependencies, then start everything with docker compose up. It is ideal for local development and testing, for example an API, database and cache together. For production orchestration across many hosts, teams use Kubernetes instead.
23

What are the Prometheus metric types?

Monitoring, Logging and SREMedium
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A counter only increases, such as total requests, and you use rate() on it. A gauge goes up and down, such as memory in use or queue length. A histogram counts observations into configurable buckets, such as request duration, and lets you compute percentiles with histogram_quantile across instances. A summary computes quantiles on the client side but cannot be aggregated across instances.
24

Two containers on the same host cannot talk to each other. What do you check?

Docker and ContainersMedium
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Check that both are on the same user-defined network with docker network inspect; the default bridge does not resolve container names. Use the service or container name and the container's internal port, not localhost and not the published host port. Confirm the app listens on 0.0.0.0 rather than 127.0.0.1. Then test with curl or nc from inside one container.
25

What are Ansible roles?

Infrastructure as Code (Terraform and Ansible)Medium
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A role is a standard folder structure that packages tasks, handlers, templates, files, variables and defaults for one purpose, for example a nginx or postgres role. Playbooks then just list roles for host groups, keeping them short and reusable across projects. Roles can be shared through Ansible Galaxy or collections, and tested with Molecule.
26

What is .gitignore and how do you stop tracking a file that is already committed?

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A .gitignore file lists patterns such as node_modules/, *.log or .env that Git should not track. It only affects untracked files, so a file already committed keeps being tracked. To stop tracking it, run git rm --cached <file>, add it to .gitignore and commit. If it held a secret, the old commits still contain it and the secret must be rotated.
27

Tell me about a time you reduced cloud costs.

AWS Cloud for DevOpsMedium
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Situation: our dev and test AWS accounts cost almost as much as production. Task: my manager asked me to cut waste without slowing teams. Action: I tagged resources by owner, found idle instances and old snapshots, scheduled non-production instances to stop at night with a Lambda, and moved CI agents to Spot. Result: non-production spend fell about 40 percent within two months.
28

How do you keep yourself updated with new DevOps tools and practices?

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I follow official release notes for tools I use, such as Kubernetes and Terraform, and read a few engineering blogs and CNCF updates weekly. I learn by doing, so I try new tools in a small home lab or free cloud tier before suggesting them. I also prepare for certifications to structure my learning, and share short notes with my team.
29

You pushed a broken commit to the shared main branch and the build is failing. What do you do?

Git and Version ControlMedium
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First restore a green main quickly: run git revert <hash> and push, which adds an undo commit without rewriting history that others have pulled. Tell the team in the channel. Then fix the issue on a branch with a proper pull request and tests. Avoid git reset with force push on main; branch protection rules should block it anyway.
30

What is DevSecOps and which security checks belong in a pipeline?

CI/CD PipelinesHard
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DevSecOps moves security earlier into the delivery process instead of a final audit. A pipeline typically adds secret scanning, static code analysis (SAST) with tools like SonarQube, dependency scanning (SCA) for vulnerable libraries, container image scanning with Trivy, infrastructure-as-code checks with Checkov, and sometimes dynamic testing (DAST) on staging. Critical findings fail the build, while lower ones create tickets.

Frequently asked questions

What happens in the DevOps telephonic interview round?

The telephonic or screening round is a 15-30 minute call with a recruiter or engineer. It checks your basics, your CV and whether you can explain DevOps concepts clearly without a screen to point at.

How do I clear the telephonic interview round?

Keep your CV in front of you and be ready to explain every line on it. Answer in short, clear sentences; there is no whiteboard, so structure matters. Take the call somewhere quiet and confirm the time in advance.

Which round comes next?

A typical order is online assessment, telephonic screening, one or two technical rounds, a managerial round and HR. Use the other round pages to practise each stage.

Practise every interview round

Online Assessment questionsTechnical Round questionsManagerial Round questionsRapid-Fire questionsHR & behavioural questionsFull mock interview

More ways to practise

Company-wise DevOps questionsExperience-wise DevOps questionsRole-wise DevOps questionsCity-wise DevOps questionsMost asked DevOps questionsScenario-based questionsPractical / hands-on questionsHR & behavioural questionsDevOps mock interviewOnline assessment questionsTechnical round questionsManagerial round questionsDevOps topic sheets