Entry questions

Scenario

A repository at /home/interview/repo contains a deployment pipeline defined in .github/workflows/deploy.yml. Currently, the pipeline deploys to both Staging and Production environments automatically on every push. This is risky because unstable code could break the Production environment immediately.

Task

Modify the workflow to implement a gated deployment strategy. Configure the staging job to run automatically on push. Configure the production job to require manual approval using GitHub Environments. Assign the production job to an environment named production. Ensure the production job only runs after staging has successfully completed. The pipeline execution can be verified with ./github-ci push.

Scenario

A repository at /home/interview/repo contains a deployment workflow that occasionally fails due to transient issues. A deployment step running ./scripts/flaky-deploy.sh fails on first attempt but succeeds on retry. The workflow needs automatic retry configuration to handle transient failures. A starter workflow file has been created at .github/workflows/deploy.yml with the basic structure.

Task

Navigate to /home/interview/repo and complete the GitHub Actions workflow at .github/workflows/deploy.yml that triggers on push events and implements automatic retry using the nick-fields/retry@v3 action. The workflow should check out code and execute ./scripts/flaky-deploy.sh with retry configuration (timeout_minutes: 2, max_attempts: 3). The workflow can be tested with ./github-ci push.

Scenario

A repository at /home/interview/repo contains a deployment workflow that occasionally hangs due to network issues or unresponsive external services. Jobs must be automatically terminated if they exceed a time limit to prevent resource waste. A starter workflow file has been created at .github/workflows/deploy.yml with the basic structure.

Task

Navigate to /home/interview/repo and complete the GitHub Actions workflow at .github/workflows/deploy.yml that triggers on push events and enforces a job-level timeout of 2 minutes using timeout-minutes: 2. The deploy job should check out code and run ./scripts/long-running-task.sh. The workflow can be tested with ./github-ci push.

Scenario

A security audit has flagged the IAM user app-deployer for having AdministratorAccess policy with far more permissions than needed. The user only needs access to:

• S3: Read (GetObject) and Add objects (PutObject), list buckets (ListBucket).
• CloudWatch Logs: Create log groups (CreateLogGroup), log streams (CreateLogStream), and put log events (PutLogEvents).

Task

1. Inspect the current policies attached to the app-deployer user
2. Remove the overly broad AdministratorAccess policy
3. Create a custom managed policy named AppDeployerPolicy that grants only the required permissions listed above
4. Attach the new policy to the app-deployer user

Note: You can use either the AWS Management Console or AWS CLI to complete this task.

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📹 Video Solution

Scenario

Your team needs a simple Lambda function for a greeting microservice.

Task

1. Create a Lambda function named hello-function that accepts a name field from event input and returns the string Hello <name> (e.g., input {"name": "World"} returns "Hello World")
2. Use the pre-created IAM role lambda-execution-role
3. Invoke the function with {"name": "World"} and verify the output is "Hello World"

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📹 Video Solution

Scenario

You need to set up a new administrative user account for regular use instead of using the root account.

Task

Create an IAM user named devops-admin with console password access. Add the user to the admin group (which should have the AdministratorAccess policy attached), and tag the user with key Role and value DevOps.

Note: You can use either the AWS Management Console or AWS CLI to complete this task.

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📹 Video Solution

Scenario

Your team needs an EC2 instance to manage IAM resources programmatically. To follow AWS security best practices, you should use an IAM role instead of embedding credentials.

Task

Create an IAM role named IAMFullAccessEC2 that:

• Allows the EC2 service to assume the role
• Has the IAMFullAccess AWS managed policy attached

Note: You can use either the AWS Management Console or AWS CLI to complete this task.

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📹 Video Solution

Scenario

Your infrastructure has two application endpoints requiring distinct monitoring strategies through Route 53 health checks, each with different protocols, ports, health check intervals, and failure thresholds.

Task

Configure two health checks:

1. web-server at 10.0.1.10 using HTTP on port 80 with a /health path, 3-failure threshold, and 30-second intervals
2. api-server at 10.0.2.10 using HTTPS on port 443, 5-failure threshold, 10-second fast intervals, inverted status enabled, and monitoring from three specific AWS regions (US East, EU Ireland, Asia Pacific Singapore)

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📹 Video Solution

Scenario

Your team is launching a new application and needs DNS configured in Route 53 for the domain example.com.

Task

1. Create a hosted zone for example.com
2. Create an A record for app.example.com pointing to 10.20.30.40 with TTL set to 60 seconds (1 minute caching)

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📹 Video Solution

Scenario

A basic landing page needs to be delivered via an EC2 instance accessible over HTTP with its own security group.

Task

1. Create a security group named web-sg permitting TCP port 80 from any IPv4
2. Launch a t2.micro instance tagged as web-1 using the web-sg security group
3. Automatically provision /var/www/html/index.html containing "Hello from web-1" during startup using user data

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📹 Video Solution

Scenario:

You have a container named cpu_test running from the image myapp:cpu that performs CPU-intensive computations. When monitoring with docker stats, the container regularly spikes to 150-200% CPU usage, consuming multiple CPU cores and impacting other services on the host.

Task:

Update the container configuration to limit CPU usage so that docker stats shows the cpu_test container consistently using less than 60% CPU during validation; You need to assign 500m CPU for that.

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📹 Video Solution

Scenario

You have a container image myapp:dualfix built from /home/interview/Dockerfile that fails during execution.

Task

Identify the issue with image as myapp:dualfix and verify it runs successfully with exit code 0.

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📹 Video Solution

Scenario:

You have a Dockerfile at /home/interview/Dockerfile that needs to be built for multiple architectures to support different hardware platforms. Currently, building with docker build only creates images for the host architecture.

Task:

Configure Docker Buildx instance named multiarch with buildx create to build the image for both amd64 and arm64 architectures using Push the multi-arch manifest to localhost:5000/myapp:multi.

Example:

Building for linux/amd64 only

Building for linux/amd64, linux/arm64
Pushing manifest list to localhost:5000/myapp:multi

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📹 Video Solution

Scenario:

You need to create a Docker volume named myvol and demonstrate cross-platform consistency - that data written from one container is readable by a different container using a different base image.

Task:

Create a Docker volume named myvol, mount it at /data, write a file hello.txt to it from an ubuntu:latest container, then read the same file from an alpine:latest container, ensuring the file exists at /var/lib/docker/volumes/myvol/_data/hello.txt on the host during validation.

Example:

# Writing from Ubuntu
ubuntu@container:/# echo "Hello from Ubuntu!" > /data/hello.txt

# Reading from Alpine
/ # cat /data/hello.txt
Hello from Ubuntu!

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📹 Video Solution

Scenario

A container image myapp:logapp continuously writes logs to stdout. Without log rotation configured, Docker's log files grow unbounded, consuming disk space and potentially filling up the filesystem.

Task

Run a container from the myapp:logapp image with the name myapp_container, enable Docker's built-in log rotation, configure the maximum size for individual log files to 10MB, retain maximum up to 3 log files during rotation, and verify the container is running successfully.

Example

Multiple rotated log files, each ≤10MB
/var/lib/docker/containers/<id>/<id>-json.log: 8.5MB
/var/lib/docker/containers/<id>/<id>-json.log.1: 10MB
/var/lib/docker/containers/<id>/<id>-json.log.2: 10MB
...
Docker automatically rotates logs at 10MB threshold

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📹 Video Solution

Scenario

You have multiple work-in-progress states saved in your Git stash stack and need to retrieve code from an older snapshot.

Task

Navigate to /home/interview/repo. Identify the third stash in the list, preview its contents, and apply it to your current working directory without removing it from the stack.

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📹 Video Solution

Scenario

You are working on the main branch and need to update config.json with changes that currently exist only on the feature-settings branch, without switching your current context.

Task

Navigate to /home/interview/repo and retrieve the config.json file from the feature-settings branch into your current working directory.

Example

# Before (Old config on main)
$ cat config.json
{ "version": "1.0.0" }

# After (New config retrieved)
$ cat config.json
{ "version": "2.0.0" }

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📹 Video Solution

Scenario:

You have a Git repository at /home/interview/repo on the main branch. A commit on the feature branch contains a bug fix you need on main, but you don't want to merge the entire feature branch.

Task:

Navigate to /home/interview/repo, identify the bug fix commit on the feature branch from the commit history, then apply it to main.

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📹 Video Solution

Scenario:

You have a Git repository at /home/interview/repo where the remote origin is currently configured with an HTTPS URL (https://github.com/user/repo.git).

Task:

Change the remote URL from HTTPS to SSH and verify the connection.

Example:

# Before (using HTTPS)
$ git remote -v
origin  https://github.com/user/repo.git (fetch)
origin  https://github.com/user/repo.git (push)

# After (using SSH)
$ git remote -v
origin  [email protected]:user/repo.git (fetch)
origin  [email protected]:user/repo.git (push)

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📹 Video Solution

Scenario:

You have a Git repository at /home/interview/repo where you've completed work on the feature-login branch. The feature is ready to be integrated into the main branch.

Task:

Merge feature-login into main and delete the feature branch in /home/interview/repo.

Example:

# Before (feature branch exists)
$ git branch
  feature-login
* main
$ git log --oneline -1 feature-login
d4e5f6a Add login validation

# After (feature merged and branch deleted)
$ git log --oneline -1 main
d4e5f6a Add login validation
$ git branch
* main

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📹 Video Solution

Scenario:

You have a Git repository at /home/interview/repo where your feature-refactor branch has four commits in the wrong logical order. The commits should be reversed (oldest to newest becomes newest to oldest) to make more sense for code review. You need to rebase this branch onto the latest main branch while reversing the commit order.

Task:

Navigate to /home/interview/repo, rebase feature-refactor onto main while reversing all commits using interactive rebase, and verify the commits appear in the correct reversed sequence with all changes preserved.

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📹 Video Solution

Scenario:

You have a Git repository at /home/interview/repo where your feature-payment branch is 32 commits behind main. You need to rebase the feature branch onto the latest main and resolve conflicts that occur during the process.

Task:

Navigate to /home/interview/repo, rebase feature-payment onto main, resolve any conflicts that arise, and verify the feature branch is now based on the latest main with all feature commits preserved.

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📹 Video Solution

Scenario

A Git repository at /home/interview/repo has a feature branch feature-login with several commits, but it was created from the wrong base branch.

Task

Rebase feature-login onto develop (it's currently based on main) while preserving all commits.

Example

# Before (feature branched from main)
* d7e8f9a (develop) Configure database settings
| * c2d3e4f (HEAD -> feature-login) Implement form validation
| * a9b0c1d Create login component
|/
* 3f4a5b6 (main) Initialize repository

# After (feature rebased onto develop)
* m8n9o0p (HEAD -> feature-login) Implement form validation
* k6l7m8n Create login component
* d7e8f9a (develop) Configure database settings
* 3f4a5b6 (main) Initialize repository

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📹 Video Solution

Scenario

You have created a commit locally that contains incorrect changes and you want to completely erase it from history.

Task

Navigate to /home/interview/repo. Remove the last commit entirely and discard all associated file changes.

Example

# Before (Bad commit exists)
$ git log --oneline -2
c3d4e5f (HEAD -> main) Bad commit - wrong changes
b2c3d4e Add feature implementation

# After (Clean history)
$ git log --oneline -2
b2c3d4e (HEAD -> main) Add feature implementation

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📹 Video Solution

Scenario

A deployment pipeline is experiencing slow build times because it performs full history clones.

Task

Navigate to /home/interview/workspace and create a shallow clone of the repository (file:///tmp/source-repo/repo.git) named shallow-repo, restricted to the latest commit only.

Example

# Verify the clone is shallow (Has only 1 commit)
$ cd shallow-repo
$ git log --oneline
a1b2c3d (HEAD -> main, origin/main, origin/HEAD) Update deployment config

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📹 Video Solution

Scenario:

You have a Git repository at /home/interview/repo where you modified three files: app.js, style.css, and config.json.

Task:

Stage only app.js and style.css for commit in the repository at /home/interview/repo, leaving config.json unstaged.

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📹 Video Solution

Scenario:

You have a Git repository at /home/interview/repo with three recent commits on the main branch that were premature and need to be reorganized.

Task:

Undo the last three commits while keeping all changes in your working directory so you can recommit them properly.

Example:

# Before (three commits exist)
$ git log --oneline -4
d4e5f6a Third commit
c3d4e5f Second commit
b2c3d4e First commit
a1b2c3d Initial commit

# After (commits undone, changes kept)
$ git log --oneline -2
a1b2c3d Initial commit

$ git status
On branch main
Changes to be committed:
  modified:   file1.txt
  modified:   file2.txt
  modified:   file3.txt

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📹 Video Solution

Scenario

A Git repository at /home/interview/repo has a feature-api branch that was created from origin/main some time ago. The branch has your commits plus merge commits from pulling updates, making it difficult to identify which commits are unique to your branch.

Task

Find commits unique to your branch compared to origin/main, exclude merge commits, write the unique commits to /home/interview/unique-commits.txt, and verify the file contains only the unique commits.

Note: The remote repository origin is already configured.

Example

# After (unique commits saved to file)
File created with unique commits from feature-api branch
Merge commits excluded
Only commits not present in origin/main are listed

Example '/home/interview/unique-commits.txt' content:
"""
ree2ras Commit message
cji29nc Commit message
ch92uhd Commit message
"""

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📹 Video Solution

Scenario

You need to create a new namespace for deploying applications.

Task

Create a namespace named playground.

Scenario

An application requires persistent storage that can be resized without downtime.

Task

Create a StorageClass, PVC, and Pod. Once the pod is running, expand the PVC to the expanded size without restarting the pod.

Property	Value
Namespace	storage
StorageClass	expandable-sc
PVC name	data-pvc
Initial size	1Gi
Expanded size	5Gi
Pod name	app-pod
Image	nginx
Mount path	/data

Template files are available at /home/interview/.

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📹 Video Solution

Scenario

A Job manifest at /home/interview/fail-job.yaml is failing with a non-zero exit status. The Job has limited retries configured.

Task

Fix the Job so it completes successfully.

Property	Value
Namespace	batch
Job name	fail-job
backoffLimit	1
Command	echo 'Success'; exit 0

Scenario

An application requires multiple configuration values mounted as files.

Task

Create a ConfigMap and mount it into a pod so all keys are accessible as files.

Property	Value
ConfigMap name	settings
Key 1	MODE=dev
Key 2	VERSION=1.0
Pod name	config-pod
Image	busybox:latest
Mount path	/etc/config
Command	sleep 3600

Scenario

A monitoring application needs read-only access to pods in the demo namespace.

Task

Set up RBAC so the ServiceAccount can only get, list, and watch Pods in that namespace.

Property	Value
Namespace	demo
ServiceAccount name	reader-sa
Role name	pod-reader
RoleBinding name	pod-reader-binding
Allowed verbs	get, list, watch
Resource	pods

Scenario

You need to deploy a web application that only receives traffic when it's ready to serve requests.

Task

Create a pod with an HTTP readiness probe that checks if the service is responding on port 80 at path /.

Property	Value
Pod name	web-ready
Image	nginx:latest
Probe type	HTTP GET
Probe port	80
Probe path	/

Scenario

An application needs guaranteed resources and limits to prevent overconsumption.

Task

Create a pod with resource requests and limits configured.

Property	Value
Pod name	resource-pod
Image	nginx:latest
CPU request	100m
Memory request	64Mi
CPU limit	200m
Memory limit	128Mi

Scenario

During peak traffic hours, a background data-processing job that is started by user devops is consuming too much CPU and slowing down user-facing services. Stopping it isn't an option because it would interrupt ongoing workflows, but you need to limit its CPU usage temporarily.

Task

Reduce the process's priority to 10 while keeping it running.

Example

# Before (high priority process)

USER       PID %CPU %MEM    VSZ     RSS   TTY      STAT START   TIME COMMAND
devops    5432 85.3 12.4 2048576 256840   ?        RN   14:35   8:23 /usr/bin/data-processor --batch

# After (priority adjusted)

USER       PID %CPU %MEM    VSZ     RSS   TTY      STAT START   TIME COMMAND
devops    5432 45.2 12.4 2048576 256840   ?        RN   14:35   8:45 /usr/bin/data-processor --batch

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📹 Video Solution

Scenario

The web server has become sluggish and users are experiencing timeout errors. Multiple worker processes are running under the nginx user, and one of them is consuming excessive CPU resources, causing the entire application to slow down.

Task

Identify the process running under the nginx user that consumes the most CPU or memory, and write its PID to /home/devops/solution.txt.

Example

# Before (multiple nginx processes, one consuming excessive resources)

USER       PID   %CPU  %MEM COMMAND
nginx     12345  92.3   4.1 nginx: worker process
nginx     12346  15.4   2.8 nginx: worker process
nginx     12347   1.2   1.0 nginx: worker process
python3   22310  45.7   6.2 python3 app.py
java      19872  37.9  12.4 java -jar app.jar

# After (PID of highest-consuming nginx process identified)

12345

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📹 Video Solution

Scenario

During an incident investigation, you pulled a massive log export from /var/log/app/access.log that's several gigabytes in size. Your analysis tools and editors can't handle the entire file at once.

Task

You need to split it into smaller, more manageable chunks for parallel review. Create a directory /tmp/log_parts/ to store the split files, split /var/log/app/access.log into smaller files containing 100 lines each, name the output files sequentially with the prefix access_part_ (e.g., access_part_aa, access_part_ab, etc.), ensure the original log file remains untouched.

Example

# Before (single large log file)

/var/log/app/access.log: 375 lines, 2.5 GB
Cannot be opened by standard analysis tools

# After (log split into manageable chunks)

100 /tmp/log_parts/access_part_aa
100 /tmp/log_parts/access_part_ab
100 /tmp/log_parts/access_part_ac
 75 /tmp/log_parts/access_part_ad

375 total

Original file intact, 4 parts created for parallel analysis

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📹 Video Solution

Scenario

The /var directory contains logs from multiple applications, and cleanup planning is needed. Some applications create their own subdirectories with nested log files.

Task

Find and count all files ending with the .log extension anywhere under /var including subdirectories, save the total count to /home/devops/log_count.txt, and use standard Linux commands to output only the total number of .log files found. Additionally, identify .log files larger than 512 KB and save the count to /home/devops/large_log_count.txt

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📹 Video Solution

Scenario

Users are complaining about slow file access. System metrics show high disk utilization.

Task

Reduce I/O activity of top offender using I/O priorities to idle. Keep critical jobs (databases, message queues, applications) at high priority.

Example

 # Before (high I/O contention)

 Total DISK READ:      45.67 M/s | Total DISK WRITE:     123.45 M/s

   TID  PRIO  USER      DISK READ  DISK WRITE  COMMAND
  5678  be/4  backup     2.34 M/s   98.76 M/s  rsync /data /backup
  3421  be/4  postgres  15.23 M/s   12.45 M/s  postgres: vacuum
  8234  be/4  appuser    8.45 M/s    3.21 M/s  /usr/bin/log-processor

 # After (non-critical jobs throttled)

 Total DISK READ:      18.34 M/s | Total DISK WRITE:      35.21 M/s

   TID  PRIO  USER      DISK READ  DISK WRITE  COMMAND
  5678  idle  backup     0.50 M/s    2.10 M/s  rsync /data /backup
  3421  be/4  postgres  15.23 M/s   12.45 M/s  postgres: vacuum
  8234  idle  appuser    1.20 M/s    0.80 M/s  /usr/bin/log-processor

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📹 Video Solution

Scenario

An application /home/interview/server.sh fails to start.

Task

Find the cause of failure and resolve it so the server can start successfully.

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📹 Video Solution

Scenario

The /tmp directory has accumulated numerous leftover folders from previous application runs and temporary scripts. Many of these directories are now empty and can be safely removed.

Task

Write a command or short script that searches through /tmp, finds all empty directories recursively, and deletes them without affecting any directories that contain files or subdirectories.

Example

# Before (empty directories present)

/tmp/old_build_cache/
/tmp/session_temp_1234/
/tmp/extract_workspace/
/tmp/app_tmp_5678/
/tmp/active_project/file.txt

# After (empty directories removed)

/tmp/active_project/file.txt

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📹 Video Solution

Scenario

Before performing a system-wide database schema migration, you've been asked to ensure that all existing .db files are safely backed up. These files may be scattered across multiple subdirectories, and simply renaming them isn't enough. You must create backup copies with the .db.bak extension, preserving directory structure and permissions.

Task

Recursively scan a given directory (/opt/data/) and create backup copies of all files ending with .db. Each backup should have the same name but with the .bak suffix added (e.g., app.db → app.db.bak) and remain in the same directory as the original file, ensuring the originals are left untouched.

Example

# Before (only original .db files exist)

/opt/data/apps/inventory.db
/opt/data/logs/session.db
/opt/data/config/settings.db

# After (backup copies created alongside originals)

/opt/data/apps/inventory.db
/opt/data/apps/inventory.db.bak
/opt/data/logs/session.db
/opt/data/logs/session.db.bak
/opt/data/config/settings.db
/opt/data/config/settings.db.bak

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📹 Video Solution

Scenario

Multiple applications write logs under /var/log, and you need to quickly check if any recent errors have been recorded.

Task

Search recursively under /var/log for all files ending with .log, print every line that contains the text ERROR, ensure the output includes both the filename and the matching line, and save the results to /home/devops/error_logs.txt.

Example

# Before (multiple log files scattered across directories)
/var/log/apache2/error.log
/var/log/apache2/access.log
/var/log/application.log
/var/log/mysql/error.log
/var/log/syslog

# After (ERROR lines found and saved to /home/devops/error_logs.txt)
/var/log/apache2/error.log:ERROR: Connection timeout to database server
/var/log/application.log:ERROR: Unable to write to cache directory
/var/log/mysql/error.log:ERROR: InnoDB: Cannot allocate memory for buffer pool
/var/log/syslog:ERROR: Disk quota exceeded for user appuser

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📹 Video Solution

Scenario

You have a log file /tmp/app_combined.log with entries from multiple servers in mixed order. Each line contains: timestamp, hostname, and action.

Task

Sort /tmp/app_combined.log by timestamp (earliest first), then by hostname for identical timestamps. Save the output to /tmp/app_sorted.log.

Example

# Before (mixed order)
2025-12-18 14:23:45 api02 POST /users/create
2025-12-18 14:22:10 cache01 CACHE_MISS key=session_abc
2025-12-18 14:22:55 api01 GET /products/list
2025-12-18 14:22:10 db02 INSERT INTO orders VALUES
2025-12-18 14:24:12 cache01 CACHE_SET key=user_profile

# After (sorted by timestamp, then hostname)
2025-12-18 14:22:10 cache01 CACHE_MISS key=session_abc
2025-12-18 14:22:10 db02 INSERT INTO orders VALUES
2025-12-18 14:22:55 api01 GET /products/list
2025-12-18 14:23:45 api02 POST /users/create
2025-12-18 14:24:12 cache01 CACHE_SET key=user_profile

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📹 Video Solution

Scenario

A server is experiencing latency spikes and intermittent timeouts. CPU and memory appear normal, suggesting a disk I/O bottleneck from a runaway process.

Task

Identify the process causing high disk I/O using real-time monitoring, then apply I/O throttling to reduce its disk priority to idle class without terminating it.

Example

# Before (high I/O process)

Total DISK READ:       125.43 M/s | Total DISK WRITE:        89.32 M/s
  TID  PRIO  USER     DISK READ  DISK WRITE  SWAPIN     IO>    COMMAND
 5432 be/4 postgres   98.45 M/s   67.23 M/s  0.00 %  95.32 % postgres: autovacuum worker

# After (I/O throttled)

Total DISK READ:        12.34 M/s | Total DISK WRITE:         8.92 M/s
  TID  PRIO  USER     DISK READ  DISK WRITE  SWAPIN     IO>    COMMAND
 5432 idle postgres    9.12 M/s    6.45 M/s  0.00 %  12.34 % postgres: autovacuum worker

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📹 Video Solution

Scenario

The /var/log/messages file has been growing unusually fast, filling up disk space within hours.

Task

Identify the process that is writing heavily to /var/log/messages by monitoring system activity in real time. Save the process details using ps and last 50 lines of logs at /home/devops/excessive_log_process.txt

Example

# Before (log file growing rapidly)

/var/log/messages: 15 GB and increasing
Disk usage: 92% and climbing

# After (responsible process identified)

Process identified: rsyslogd (PID 1234)
Confirmed active writes to /var/log/messages

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📹 Video Solution

Scenario

System resources are being consumed by an unusually large process tree. You need to identify the parent process with the most children and document its hierarchy.

Task

Identify the process tree with the highest number of child processes and save its hierarchy—including PIDs and full command names (arguments)—to: /home/devops/process_tree_report.txt.

Linux provides the pstree command to display full hierarchical process trees, including PIDs and command arguments.

Example

The file /home/devops/process_tree_report.txt should look similar to this:

spawn_many_workers.sh,159 /home/devops/spawn_many_workers.sh
 ├─sleep,209 infinity
 ├─spawn_many_workers.sh,190 /home/devops/spawn_many_workers.sh
 │  └─sleep,220 60
 ├─spawn_many_workers.sh,191 /home/devops/spawn_many_workers.sh
 ...

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📹 Video Solution

Scenario

A Linux server is under review for stability and recent performance evaluation.

Task

Use the uptime command to determine how long the server has been running and extract the 15-minute load average as a floating-point number (e.g., 0.45). Save the uptime to /home/devops/uptime.txt and the 15-minute load average to /home/devops/loadavg.txt.

Example

Contents of `/home/devops/uptime.txt`: `2 days, 5:37`

Contents of `/home/devops/loadavg.txt`: `0.45`

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📹 Video Solution

Scenario

Users are reporting random timeouts. You need to determine whether packet loss occurs on the local network, upstream gateway, or public internet.

Task

Find your default gateway IP, ping the gateway, DNS server (8.8.8.8), and google.com (5 times each), collect packet loss and average latency from each, and write results to /tmp/network_diagnostics.txt showing target name, IP/hostname, packet loss percentage, and average latency.

Example

File: /tmp/network_diagnostics.txt

Gateway (192.168.1.1): loss=0% avg=1.2 ms
DNS (8.8.8.8): loss=0% avg=15.8 ms
Internet (google.com): loss=20% avg=83.5 ms

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📹 Video Solution

Scenario

A security audit found several unauthorized applications listening on high ports (range 8000-9000).

Task

Scan the system for listening TCP/UDP ports between 8000 and 9000. Identify the Process IDs (PIDs) bound to these ports and terminate the associated services.

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📹 Video Solution

Scenario

Network latency issues were reported due to opening too many TCP connections.

Task

Inspect active sockets along with the processes that own them to identify which application is responsible for the excessive connection count. Save all currently active TCP/UDP connections (ESTABLISHED, LISTEN, TIME_WAIT, etc.) output to /tmp/active_tcp.txt

Example

Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 192.168.1.50:22         192.168.1.100:54321     ESTABLISHED 1234/sshd
tcp        0      0 192.168.1.50:3306       192.168.1.75:41234      ESTABLISHED 5678/mysqld
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      9012/nginx
tcp        0      0 127.0.0.1:6379          127.0.0.1:45678         ESTABLISHED 3456/redis-server
tcp        0      0 192.168.1.50:443        203.0.113.45:12345      ESTABLISHED 9012/nginx

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📹 Video Solution

Scenario

You need to reach a remote subnet that isn't covered by the default route, but you don't want to make any permanent configuration changes.

Task

Check the current routing table to confirm the 10.20.0.0/16 subnet is not present, add a temporary static route for the 10.20.0.0/16 subnet via gateway 192.168.1.1 using interface veth0.

Example

# Before (no route to remote subnet)

10.20.0.0/16 subnet not in routing table
Cannot reach remote network
Need temporary access without permanent changes

# After (temporary route added)

10.20.0.0/16 via 192.168.1.1 dev veth0

Route active and verified
Remote subnet accessible

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📹 Video Solution

Scenario

Your monitoring alerts indicate that DNS resolution might be inconsistent across servers, and you need to confirm both IPv4 and IPv6 records for a given domain.

Task

Add IPv4 and IPv6 address entries for the domain example.local to /etc/hosts using the format <ip_address> <hostname> with each record on a separate line.

Example

198.51.100.42 example.local
2001:db8:85a3::8a2e:370:7334 example.local

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📹 Video Solution