Curated interview practice questions with answers. These are practice scenarios, not a verified list of past interview questions.
About Red Hat hiring for DevOps roles
Red Hat is an open source software company, now part of IBM, known for Red Hat Enterprise Linux, OpenShift and Ansible. It provides enterprise Linux, hybrid cloud, container and automation platforms with subscription-based support. In India it has a large presence in Pune and Bengaluru, hiring software engineers, quality engineers, support engineers and consultants.
For DevOps roles, this Red Hat practice set focuses most on Linux and Shell Scripting (7), CI/CD Pipelines (5), Kubernetes (4), Infrastructure as Code (Terraform and Ansible) (4). It has 1 easy, 18 medium, 11 hard questions, so you can start easy and work up to the harder ones.
Company type
Product
Headquarters
Raleigh, North Carolina, USA
Main India offices
Pune, Bengaluru
Red Hat DevOps interview process
Online assessment or resume screening
Technical round 1 (Linux + programming)
Technical round 2 (domain or open source)
Hiring manager and HR round
Typical pattern based on public candidate experiences. Rounds vary by role, team and year.
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01
How do you build and push a Docker image from a pipeline?
# shell steps in any CI tool
IMAGE=registry.example.com/shop/api
TAG=$(git rev-parse --short HEAD)
echo "$REG_PASS" | docker login registry.example.com -u "$REG_USER" --password-stdin
docker build -t $IMAGE:$TAG .
docker push $IMAGE:$TAG
Tag with the commit SHA so each image is traceable and immutable; avoid relying on latest. Credentials come from the CI secret store, and --password-stdin keeps them out of process lists.
A zombie is a process that has exited but whose parent has not yet read its exit status with wait(), so it still holds a PID entry and shows state Z. An orphan is a running process whose parent died; it is adopted by PID 1, which reaps it later. Many zombies indicate a buggy parent; fixing or restarting the parent clears them.
03
What is load average in Linux and how do you read it?
Load average is the average number of processes running or waiting for CPU (and uninterruptible I/O) over 1, 5 and 15 minutes, shown by uptime or top. Compare it with the number of CPU cores: a load of 4 on a 4-core machine means full use, while 12 means work is queuing. A high load with low CPU use often points to disk or network I/O waits.
04
Write a bash script that checks whether a service is running and restarts it if not.
#!/bin/bash
set -u
SERVICE="nginx"
if ! systemctl is-active --quiet "$SERVICE"; then
echo "$(date) $SERVICE down, restarting" >> /var/log/svc-check.log
systemctl restart "$SERVICE"
if ! systemctl is-active --quiet "$SERVICE"; then
echo "$SERVICE failed to start" | mail -s "ALERT" ops@example.com
fi
fi
Run it from cron every few minutes; a real setup would rely on systemd Restart= plus monitoring.
05
You need one pipeline that deploys to dev, staging and production with approval before production. How do you design it?
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.
GitOps uses a Git repository as the single source of truth for the desired state of infrastructure and applications. An agent running in the cluster, such as Argo CD or Flux, continuously compares the live state with Git and pulls changes to reconcile drift. Deployments become pull requests, giving review, audit history and easy rollback by reverting a commit. CI builds images; GitOps handles deployment.
07
Someone made an S3 bucket with customer files public. What do you do?
Immediately block public access on the bucket and remove the public policy or ACLs. Check S3 server access logs or CloudTrail data events to see whether objects were downloaded, and involve security if customer data was exposed. Then enable Block Public Access at the account level, use AWS Config rules to detect public buckets, and require bucket changes through reviewed IaC.
08
Write PromQL queries for request rate, error rate and p95 latency.
# requests per second per service over 5 minutes
sum by (service) (rate(http_requests_total[5m]))
# error ratio (5xx)
sum(rate(http_requests_total{status=~"5.."}[5m]))
/ sum(rate(http_requests_total[5m]))
# p95 latency from a histogram
histogram_quantile(0.95,
sum by (le) (rate(http_request_duration_seconds_bucket[5m])))
rate() works on counters and handles resets; the le label holds histogram bucket bounds.
09
How do you use stored credentials inside a Jenkins pipeline?
pipeline {
agent any
environment {
SONAR_TOKEN = credentials('sonar-token')
}
stages {
stage('Push') {
steps {
withCredentials([usernamePassword(credentialsId: 'docker-hub',
usernameVariable: 'USER', passwordVariable: 'PASS')]) {
sh 'echo $PASS | docker login -u $USER --password-stdin'
}
}
}
}
}
Jenkins masks these values in console output. Use single quotes in sh so Groovy does not interpolate the secret.
10
During rolling updates some user requests fail. How do you get true zero-downtime deployments?
Add a proper readiness probe so new pods get traffic only when ready. Set maxUnavailable to 0 and maxSurge to 1 or more. Handle SIGTERM gracefully and add a short preStop sleep so endpoints update before the old pod stops accepting connections, with terminationGracePeriodSeconds long enough to drain requests. Add a PodDisruptionBudget for node maintenance too.
11
Your Docker image is 1.5 GB. How do you reduce its size?
Switch to a slimmer base image such as a slim or distroless variant. Use a multi-stage build so compilers and build caches stay out of the final image. Combine package installs and clean caches in the same RUN layer. Add a .dockerignore to exclude .git, node_modules and test data. Then inspect remaining layers with docker history or the dive tool.
12
The monthly AWS bill suddenly doubled. How do you investigate and fix it?
Open Cost Explorer and group by service, account and tag to find the spike, then drill into usage type. Common causes are forgotten instances, unattached EBS volumes, NAT Gateway data transfer, oversized RDS, or logs retained forever. Fix the source, then set AWS Budgets alerts, enforce tagging, right-size using Compute Optimizer, and use Savings Plans or Spot for steady or batch workloads.
13
Describe how you handled an on-call incident late at night.
Situation: at 2 AM I got an alert that checkout error rates crossed 10 percent. Task: restore service as on-call engineer. Action: I checked dashboards, saw a node pool had scaled down and pods were pending, scaled it manually, and posted updates in the incident channel. Result: errors cleared in 20 minutes, and next day I fixed the autoscaler settings and wrote the post-mortem.
14
A production server is very slow. How do you troubleshoot high CPU usage?
Start with uptime and top or htop to see load and which processes use CPU. Check whether it is user, system or iowait time, and use pidstat or ps -eo pid,pcpu,cmd --sort=-pcpu for detail. For a Java process, take thread dumps; for others, use perf or strace. Correlate with recent deployments, cron jobs or traffic spikes before deciding to scale, roll back or fix code.
15
How do you manage dev, staging and production environments with Terraform?
Keep shared logic in versioned modules and create a separate root configuration per environment, each with its own backend state and tfvars, for example envs/dev and envs/prod. This isolates state so a mistake in dev cannot touch prod. Workspaces are an option for near-identical environments but share backend config. Promote module versions from dev to prod through pull requests.
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.
helm repo add bitnami https://charts.bitnami.com/bitnami
helm repo update
helm install my-redis bitnami/redis -n cache --create-namespace
helm upgrade my-redis bitnami/redis -f values-prod.yaml
helm list -A
helm rollback my-redis 1
helm uninstall my-redis -n cache
helm template ./mychart -f values.yaml # render locally
Helm is the package manager for Kubernetes. A chart is a set of templated manifests, and values files customise it per environment.
18
What are the four golden signals, and the RED and USE methods?
The four golden signals are latency, traffic, errors and saturation. RED, for request-driven services, tracks rate, errors and duration. USE, for resources such as CPU, disks and network, tracks utilisation, saturation and errors. RED tells you whether users are hurting; USE helps find which resource is the bottleneck. Together they give a solid starting set of dashboards and alerts.
19
How do you count unique client IP addresses in an nginx access log?
awk '{print $1}' /var/log/nginx/access.log | sort | uniq -c | sort -rn | head -10
# total number of unique IPs
awk '{print $1}' access.log | sort -u | wc -l
The first field in the default log format is the client IP. uniq -c only collapses adjacent lines, so sort must run before it; the final sort -rn shows the busiest IPs first.
20
The host disk is filling up because of Docker. How do you clean up and prevent it?
Check usage with docker system df. Remove stopped containers, dangling images and unused networks with docker system prune, and old build cache with docker builder prune; be careful with the volumes flag. Container logs are a common culprit, so configure log rotation with max-size and max-file in daemon.json. In CI agents, schedule regular pruning jobs.
Run kubectl describe node to see conditions such as MemoryPressure, DiskPressure or a kubelet that stopped posting status. SSH in and check systemctl status kubelet, the container runtime, journalctl -u kubelet, disk space and network to the API server. Pods on the node are evicted after a timeout. Cordon and drain it, fix or replace the node, and in cloud setups let the node group recreate it.
22
Tell me about a time you introduced a new tool or practice to your team.
Situation: new developers took two days to set up our app locally because of different OS versions and manual database installs. Task: I wanted to make onboarding easy. Action: I created a Docker Compose setup with the app, database and seed data, wrote a short README and demoed it. Result: setup dropped to under an hour and the team adopted it for CI.
23
Tell me about a time you disagreed with a code review comment.
Situation: a reviewer asked me to replace a simple retry loop in our deploy script with a heavy external library. Task: I felt it added risk. Action: I explained my reasoning, shared a small benchmark and failure tests, and asked what concern they had; it was about backoff. Result: I added exponential backoff to my version, they approved, and we documented the pattern.
24
Your CI pipeline takes 40 minutes. How would you speed it up?
Measure first: find which stages take longest. Then cache dependencies and Docker layers, run independent stages and test suites in parallel, split tests across agents, and run only affected modules in a monorepo. Move slow end-to-end tests to a later stage or nightly run while keeping fast unit tests on every commit. Use bigger or autoscaled agents if they are the bottleneck.
25
df shows the disk is 100 percent full but du does not find large files. What is happening?
Usually a large file was deleted while a process still holds it open, so the space is not released. Run lsof +L1 or lsof | grep deleted to find the process and file. Restarting or reloading that process frees the space; if you cannot restart, truncate the file through /proc/<pid>/fd/<n>. The fix is proper log rotation with copytruncate or a reopen signal.
26
How would you convince a team that manages servers by hand to adopt Infrastructure as Code?
I would start with their pain, such as slow environment setup or outages from manual changes, rather than the tool. Then I would codify one small, visible piece, for example a new staging environment, and show it rebuilt in minutes with a reviewed pull request. I would pair with team members, write simple docs and expand gradually, measuring time saved and incidents avoided.
27
An application logs 'Too many open files'. How do you fix it?
The process has hit its file descriptor limit. Check usage with ls /proc/<pid>/fd | wc -l and the limit in /proc/<pid>/limits. Raise it through LimitNOFILE in the systemd unit or /etc/security/limits.conf, then restart. But also look for a leak: sockets or files not closed in code keep growing and will hit any limit. Raising the limit alone only buys time.
28
You get an alert that the company website is down. What are your first steps?
Acknowledge the alert so others know you are on it. Check whether it is really down from outside with curl or an uptime checker, and whether it is all users or one region. Look at recent deployments or changes, then load balancer health, application logs and the database. If a recent change caused it, roll back first. Inform the team and escalate if you cannot fix it quickly.
29
How do you use git bisect to find the commit that introduced a bug?
git bisect start
git bisect bad # current commit has the bug
git bisect good v1.4.0 # last known good tag
# Git checks out a middle commit; test it, then mark it
git bisect good # or: git bisect bad
# repeat until Git prints the first bad commit
git bisect reset
# automate with a test script
git bisect run ./run-tests.sh
Bisect is a binary search, so 1000 commits need about 10 tests.
30
How do you handle secrets in Terraform and Ansible?
Do not hard-code secrets in .tf files or playbooks. In Terraform, read them from AWS Secrets Manager or Vault data sources, mark variables sensitive, and protect state because it may still hold values. In Ansible, encrypt secret variable files with ansible-vault and supply the vault password from CI secrets, or look up values from Vault at runtime. Rotate anything exposed in Git.
Tips to crack the Red Hat DevOps interview
Get comfortable with Linux commands, shell scripting, processes, permissions and networking, which are central to many Red Hat roles.
Contribute to an open source project or show GitHub work, since Red Hat values public collaboration and community involvement.
Learn the basics of containers, Kubernetes and Ansible, and consider Red Hat certifications such as RHCSA for support roles.
Keep a one-minute story ready for every project on your CV: problem, your part, tools, result.
Practise the hard questions on this page aloud; Red Hat interviewers usually ask follow-ups on your first answer.
Frequently asked questions
How many rounds are there in the Red Hat DevOps interview?
Candidates usually go through 4 stages: Online assessment or resume screening; Technical round 1 (Linux + programming); Technical round 2 (domain or open source); Hiring manager and HR round. The exact rounds change with the role, team, location and your experience, so confirm the process with the recruiter.
Which topics should I prepare for the Red Hat DevOps interview?
This practice set leans on Linux and Shell Scripting (7), CI/CD Pipelines (5), Kubernetes (4), Infrastructure as Code (Terraform and Ansible) (4). Revise those first, then practise explaining one or two of your own projects end to end, because most Red Hat interviewers ask you to walk through real work.
Are these the exact questions asked at Red Hat?
No. These are curated practice questions that match the skills and difficulty usually tested in product interviews like Red Hat's. They are not a leaked or verified list of past questions.
Where does Red Hat hire DevOps professionals in India?
Red Hat has large teams in Pune, Bengaluru. Openings and locations change often, so check the Red Hat careers page and filter by city and experience.