EC2, RDS, CloudWatch and S3 are four core Amazon Web Services that together cover compute, managed databases, monitoring and storage. A candidate who has worked with all four has usually built and run real applications on AWS. For hiring teams, the combination is a useful signal, but only if you verify it with hands on tasks instead of trusting the resume.
This entry explains what each service means in a candidate’s experience, which roles need it, and how to test AWS skills with Glider AI Technical Assessments.
What each service means on a resume
- Amazon EC2 is virtual servers. Experience means launching and sizing instances, configuring security groups, using auto scaling and keeping servers patched.
- Amazon RDS is managed relational databases such as MySQL and PostgreSQL. Experience means setting up instances, backups, read replicas, failover and performance tuning.
- Amazon CloudWatch is monitoring and logging. Experience means building dashboards, setting alarms, reading logs and responding to incidents.
- Amazon S3 is object storage. Experience means managing buckets, access policies, lifecycle rules, versioning and encryption.
Together they describe a common stack: an application on EC2, its data in RDS, files and backups in S3, and CloudWatch watching all of it.
AWS S3 vs EC2: what is the difference?
Candidates often list S3 and EC2 together, but they solve different problems. Knowing the difference is a quick test of real AWS experience.
Amazon EC2 (Elastic Compute Cloud) gives you virtual machines. An Amazon EC2 instance has an operating system, CPU, memory, and attached block storage, and teams use it to run applications, APIs, and batch jobs. You pay for compute resources while the instance runs, and you scale by adding or resizing instances.
Amazon S3 (Simple Storage Service) is an object storage service. It stores files as objects inside buckets and serves them over HTTP. S3 storage has no server to manage and scales to almost any amount of data, which is why teams use it for backups, static website assets, logs, and data lakes.
- What it does: EC2 runs code; S3 stores objects
- Storage model: EC2 uses attached volumes (Amazon Elastic Block Store) with a normal file system; S3 uses buckets and keys, not folders and disks
- Pricing: EC2 bills for each running instance by time; S3 bills for stored data, requests, and transfer
- Typical use: EC2 for web servers and workloads that need a full OS; S3 for files, media, archives, and analytics data
In an assessment, a simple pair of tasks shows whether a candidate understands both: ask them to create a bucket with the right access policy, then launch an instance that reads from it using an IAM role instead of hard coded keys.
Why this combination matters when hiring
Listing one AWS service tells you little. Listing all four, with specifics, suggests the candidate has owned an application end to end on AWS rather than touching one piece. That is the experience most cloud, DevOps and backend roles need.
The catch is that AWS names are easy to add to a resume. Recruiters often cannot tell whether “managed RDS” means tuning a production database under load or clicking through a console tutorial. Interviews help, but senior engineers lose time on candidates who were never ready.
What to assess for each service
| Service | What a qualified candidate should be able to do | How to test it |
|---|---|---|
| EC2 | Launch, size and secure instances; configure auto scaling | Task: deploy an app behind a load balancer with correct security groups |
| RDS | Configure backups, replicas and access; troubleshoot slow queries | Task: fix a misconfigured database connection and explain backup strategy |
| CloudWatch | Build alarms and dashboards; trace an incident through logs | Scenario: diagnose a latency spike from logs and metrics |
| S3 | Set bucket policies, encryption and lifecycle rules | Task: lock down a public bucket and add lifecycle rules |
| Combined | Connect the four services securely with least privilege IAM | Scenario: design a small, monitored, backed up application stack |
Roles that need EC2, RDS, CloudWatch and S3 skills
- Cloud engineers who build and run infrastructure on AWS
- DevOps and site reliability engineers who own deployment, monitoring and incident response
- Backend developers who deploy services and manage their data stores
- Solutions architects who design AWS environments for clients or internal teams
- Data engineers who move data between RDS, S3 and analytics tools
Depth differs by role. A backend developer may need working knowledge of RDS and S3. A site reliability engineer should be fluent in CloudWatch alarms and incident workflows.
Interview questions to pair with a hands on test
- How did you size and secure EC2 instances for a production workload?
- Describe your RDS backup and recovery setup. Have you ever restored from a snapshot?
- Which CloudWatch alarms do you set first for a new service, and why?
- How do you make sure an S3 bucket is not publicly exposed?
- Walk me through an incident you diagnosed with CloudWatch. What was the root cause?
Strong answers name specific settings, explain tradeoffs between cost and reliability, and describe what went wrong as well as what went right.
How Glider AI helps you hire cloud talent
Glider AI, a Findem company, helps hiring teams validate cloud skills before final interviews. Glider AI Technical Assessments cover 250+ languages and technologies, including cloud, with in depth skill reports you can share with hiring managers. Top candidates can be scored and shortlisted automatically, and AI proctoring with 50+ checkpoints helps prevent fraud and plagiarism.
For roles that need full environment work, coding simulations include DevOps tasks such as config debugging, server routing setup and deployment automation, and a virtual desktop that simulates a complete Linux machine. To compare adjacent skills, see the skills glossary or the skill test library.
Frequently asked questions
What do EC2, RDS, CloudWatch and S3 do?
EC2 provides virtual servers, RDS provides managed relational databases, CloudWatch provides monitoring, logs and alarms, and S3 provides object storage. Used together, they support a typical web application: compute on EC2, data in RDS, files and backups in S3, and CloudWatch tracking health and performance.
Why do employers look for EC2, RDS, CloudWatch and S3 experience together?
The combination shows a candidate has likely run a full application on AWS, not just one component. It covers compute, data, storage and monitoring, which are the responsibilities most cloud, DevOps and backend roles share.
How do you assess AWS skills in a candidate?
Give candidates hands on tasks in a realistic environment: deploy an application, secure a bucket, configure a database backup or diagnose an incident from logs. Review the result and the reasoning, monitor the session, and follow up in a technical interview about the choices they made.
Is AWS certification enough to prove AWS skills?
Certification shows study and baseline knowledge, which is useful. It does not prove the candidate can configure, secure and troubleshoot a live environment. Pair certifications with a hands on assessment that mirrors the work the role requires.
What AWS skills does a cloud engineer need?
Most cloud engineers need EC2, VPC networking, IAM, RDS or another managed database, S3, CloudWatch and infrastructure as code tools. They should also understand cost control, security best practices and incident response, since those decide how well an environment runs day to day.
What AWS interview questions should hiring managers ask?
Ask about real decisions: how the candidate sized instances, set up backups, chose alarms, secured buckets and handled incidents. Ask what went wrong and how they fixed it. Specific, experience based answers are more useful than definitions of each service.
Verify AWS skills before the final round
The four services on a resume are a starting point. A proctored, hands on task shows whether the candidate can run them in production. See how Glider AI Technical Assessments help your team confirm cloud skills before senior engineers spend time in interviews.