The largest single domain on the AWS Certified Cloud Practitioner (CLF-C02) exam is Cloud Technology and Services, weighted at 34% — more than a third of your score. It tests whether you can name AWS’s core services, place each in the right category, and pick the right one for a described scenario. You won’t be asked to architect anything or write code; you’ll be asked things like “Which AWS service provides object storage?” or “A team needs a managed NoSQL database — which service?”
This guide is a structured tour of those core services, organized the way AWS organizes them: compute, storage, networking, databases, application integration, and management. For each category you get a plain-English explanation, the specific services the exam expects you to recognize, and a when-to-use-what table. If you want the exam logistics and full blueprint first, read the AWS Cloud Practitioner exam guide for 2026 and the domains breakdown.
First, How AWS Organizes the World
Before the services, know the global infrastructure they run on — it shows up in questions constantly:
| Term | What it is |
|---|---|
| Region | A physical geographic area (e.g. us-east-1) containing multiple data centers. You choose Regions for latency, compliance, and price. |
| Availability Zone (AZ) | One or more discrete data centers within a Region, isolated for fault tolerance. Deploying across AZs gives you high availability. |
| Edge Location | A site used by CloudFront and other edge services to cache content close to users. There are far more edge locations than Regions. |
| Local Zone / Wavelength | Infrastructure that places compute closer to end users or 5G networks for ultra-low latency. |
The rule of thumb the exam rewards: spread across multiple AZs for high availability; choose the Region nearest your users (and that meets compliance) for performance and data residency.
Compute: Running Your Code
Compute is where your applications execute. AWS offers a spectrum from full virtual machines to fully serverless functions.
The services to know
- Amazon EC2 (Elastic Compute Cloud) — resizable virtual machines. The foundational compute service. You pick an instance type, OS, and size.
- AWS Lambda — serverless functions. You upload code; AWS runs it on demand and you pay only for execution time. No servers to manage.
- Amazon ECS / Amazon EKS — container orchestration for Docker workloads (ECS is AWS-native; EKS is managed Kubernetes).
- AWS Fargate — serverless compute for containers, so you run ECS/EKS tasks without managing EC2 instances.
- AWS Elastic Beanstalk — platform-as-a-service that deploys and manages web apps for you (provisions EC2, load balancing, scaling automatically).
- EC2 Auto Scaling — automatically adds or removes EC2 instances based on demand.
- Elastic Load Balancing (ELB) — distributes incoming traffic across multiple targets for availability and scale.
EC2 instance families (recognize the categories)
| Family | Optimized for | Example use |
|---|---|---|
| General Purpose (T, M) | Balanced compute/memory | Web servers, small databases |
| Compute Optimized (C) | High CPU | Batch processing, gaming servers |
| Memory Optimized (R, X) | Large RAM | In-memory databases, analytics |
| Storage Optimized (I, D) | High disk throughput | Data warehousing, big data |
| Accelerated Computing (P, G) | GPUs | Machine learning, rendering |
When to use what: Need full control of the OS? EC2. Event-driven code with no servers to manage? Lambda. Running containers without managing nodes? Fargate. Want AWS to handle deployment of a standard web app? Elastic Beanstalk.
EC2 also has several pricing models (On-Demand, Reserved Instances, Spot, Savings Plans, Dedicated Hosts). Those belong to the Billing domain — the pricing, billing and cost management guide covers them in detail.
Storage: Where Your Data Lives
AWS storage splits into three fundamental types — object, block, and file — and the exam loves to test whether you can tell them apart.
The services to know
- Amazon S3 (Simple Storage Service) — object storage for any amount of data: backups, media, static websites, data lakes. Virtually unlimited, accessed over HTTP(S).
- Amazon EBS (Elastic Block Store) — block storage volumes attached to a single EC2 instance, like a virtual hard drive.
- Amazon EFS (Elastic File System) — file storage (NFS) that many EC2 instances can mount simultaneously.
- Amazon FSx — managed file systems for Windows File Server and Lustre.
- Instance Store — temporary block storage physically attached to the host; data is lost when the instance stops.
- AWS Storage Gateway — hybrid storage bridging on-premises environments to AWS.
- AWS Backup — centralized, policy-based backup across AWS services.
S3 storage classes
S3 isn’t one tier — it’s a family priced by how often you access data:
| Class | Best for |
|---|---|
| S3 Standard | Frequently accessed data |
| S3 Intelligent-Tiering | Unknown or changing access patterns (auto-moves data) |
| S3 Standard-IA / One Zone-IA | Infrequently accessed data (One Zone = cheaper, single AZ) |
| S3 Glacier Instant Retrieval | Archive needing millisecond access |
| S3 Glacier Flexible Retrieval | Archive, minutes-to-hours retrieval |
| S3 Glacier Deep Archive | Lowest cost, 12-hour retrieval, long-term compliance |
When to use what: Object storage for files, backups, or a static site? S3. A disk for one EC2 instance? EBS. A shared file system for many instances? EFS. Cheap long-term archive? S3 Glacier Deep Archive.
Networking and Content Delivery
Networking services connect, isolate, and accelerate your resources.
The services to know
- Amazon VPC (Virtual Private Cloud) — your own logically isolated network in AWS, with subnets, route tables, and gateways.
- Security Groups and Network ACLs — the two firewall layers (compared below).
- Amazon Route 53 — scalable DNS and domain registration, with health checks and routing policies.
- Amazon CloudFront — the content delivery network (CDN) that caches content at edge locations close to users.
- Amazon API Gateway — create, publish, and secure REST/HTTP/WebSocket APIs.
- AWS Direct Connect — a dedicated private network connection from on-premises to AWS.
- AWS VPN — encrypted tunnels from on-premises to your VPC over the internet.
- AWS Global Accelerator — routes user traffic over the AWS backbone for better performance.
Security Groups vs. Network ACLs
This comparison is a near-guaranteed exam question:
| Feature | Security Group | Network ACL |
|---|---|---|
| Operates at | Instance (ENI) level | Subnet level |
| State | Stateful (return traffic auto-allowed) | Stateless (must allow both directions) |
| Rules | Allow only | Allow and deny |
| Evaluation | All rules evaluated | Rules evaluated in number order |
When to use what: DNS and domain routing? Route 53. Caching content globally to reduce latency? CloudFront. A dedicated, consistent on-prem link? Direct Connect. A quick encrypted connection over the internet? Site-to-Site VPN.
Databases: Managed Data Stores
AWS managed database services remove the operational burden of patching, backups, and replication. Knowing relational vs. non-relational vs. analytics is what the exam checks.
The services to know
- Amazon RDS (Relational Database Service) — managed relational databases: MySQL, PostgreSQL, MariaDB, Oracle, and SQL Server.
- Amazon Aurora — AWS’s high-performance, MySQL/PostgreSQL-compatible relational engine.
- Amazon DynamoDB — fully managed, serverless NoSQL key-value database with single-digit-millisecond performance.
- Amazon ElastiCache — managed in-memory caching (Redis or Memcached) to speed up read-heavy apps.
- Amazon Redshift — managed data warehouse for analytics over large datasets.
- Amazon Aurora / RDS read replicas & Multi-AZ — for scaling reads and for high availability.
Choosing a database
| Need | Service |
|---|---|
| Traditional relational database (SQL) | Amazon RDS |
| Cloud-native, high-performance relational | Amazon Aurora |
| Serverless NoSQL, massive scale | Amazon DynamoDB |
| In-memory cache for speed | Amazon ElastiCache |
| Analytics / data warehouse | Amazon Redshift |
When to use what: Structured data with joins and transactions? RDS/Aurora. Flexible schema and huge scale with simple lookups? DynamoDB. Reporting across terabytes? Redshift.
Application Integration and Management
Two more groups round out the domain. You only need recognition-level familiarity.
Application integration (decoupling services)
- Amazon SQS (Simple Queue Service) — fully managed message queue for decoupling components.
- Amazon SNS (Simple Notification Service) — pub/sub messaging and notifications (email, SMS, HTTP).
- Amazon EventBridge — event bus that routes events between AWS services and apps.
Management and monitoring
- Amazon CloudWatch — metrics, logs, alarms, and dashboards for monitoring.
- AWS CloudTrail — records API calls for auditing and governance.
- AWS CloudFormation — infrastructure as code; provision resources from templates.
- AWS Trusted Advisor — automated checks for cost, security, performance, and limits.
- AWS Systems Manager — operational management of resources at scale.
Note the classic distinction: CloudWatch monitors performance (“what is happening”); CloudTrail records who did what (“who made this API call”). That contrast is a frequent exam question and is also covered in the shared responsibility model guide.
Master Service Cheat Sheet
| Category | Service | One-line role |
|---|---|---|
| Compute | EC2 | Virtual machines |
| Compute | Lambda | Serverless functions |
| Compute | Elastic Beanstalk | Managed app deployment |
| Storage | S3 | Object storage |
| Storage | EBS | Block storage for one instance |
| Storage | EFS | Shared file storage |
| Networking | VPC | Isolated private network |
| Networking | Route 53 | DNS |
| Networking | CloudFront | CDN |
| Database | RDS / Aurora | Managed relational DB |
| Database | DynamoDB | Managed NoSQL DB |
| Database | Redshift | Data warehouse |
| Integration | SQS / SNS | Queue / pub-sub messaging |
| Management | CloudWatch | Monitoring |
| Management | CloudTrail | API auditing |
Practice with Realistic Exam Questions
The Cloud Technology and Services domain is won by recognition speed. The exam doesn’t ask you to build with EC2 or DynamoDB — it asks you to instantly map a one-sentence scenario to the right service. That recall is built by answering scenario questions over and over until “managed NoSQL” reflexively returns “DynamoDB” and “object storage” returns “S3.”
Sailor.sh’s AWS Certified Cloud Practitioner (CLF-C02) Mock Exam Bundle gives you full-length, exam-style practice exams with the same scenario phrasing and service-selection style you’ll face on test day, plus explanations that reinforce why a given service is the right answer. Combine the practice exams with a structured Cloud Practitioner study plan and warm up with the free Cloud Practitioner practice questions. If you’re brand new to AWS, start with the Cloud Practitioner for beginners guide, and if you’re weighing your next step, compare it with the Cloud Practitioner vs. Solutions Architect path.
Frequently Asked Questions
How many AWS services do I need to know for the Cloud Practitioner exam?
You don’t need to know all 200+ AWS services in depth. The CLF-C02 expects recognition-level familiarity with the core services in each category — compute (EC2, Lambda), storage (S3, EBS, EFS), networking (VPC, Route 53, CloudFront), databases (RDS, DynamoDB, Redshift), plus key management and integration services. Knowing what each does and when to use it is enough.
What is the difference between S3, EBS, and EFS?
S3 is object storage accessed over HTTP for files, backups, and static sites. EBS is block storage — a virtual disk attached to a single EC2 instance. EFS is a shared file system (NFS) that many EC2 instances can mount at once. The exam frequently tests this object-vs-block-vs-file distinction.
When should I use EC2 instead of Lambda?
Use EC2 when you need full control of the operating system, long-running processes, or specific instance types (e.g. GPU). Use Lambda for short, event-driven functions where you don’t want to manage any servers and want to pay only for execution time. Lambda has execution-time limits, so steady, long-running workloads usually fit EC2 or containers better.
What is the difference between a security group and a network ACL?
A security group is a stateful firewall at the instance level that supports allow rules only; return traffic is automatically permitted. A network ACL is a stateless firewall at the subnet level that supports both allow and deny rules and evaluates them in number order. Security groups are the first thing most exam scenarios reach for.
Is DynamoDB or RDS the right choice on the exam?
Choose RDS (or Aurora) when the scenario describes a relational/SQL database with structured data, joins, or transactions. Choose DynamoDB when it mentions NoSQL, key-value or document data, serverless, or massive scale with simple lookups. Watch for the keyword “NoSQL” or “managed serverless database” — that’s almost always DynamoDB.
Which domain are these services part of?
Core services fall under the Cloud Technology and Services domain, the largest at 34% of the CLF-C02. The other domains are Cloud Concepts (24%), Security and Compliance (30%), and Billing, Pricing and Support (12%). See the full domains breakdown for how to split your study time.
Conclusion
The Cloud Technology and Services domain rewards breadth, not depth. You don’t need to configure a VPC or tune a DynamoDB table — you need to instantly recognize that object storage is S3, a virtual machine is EC2, a managed NoSQL database is DynamoDB, and a CDN is CloudFront. Learn the categories, learn one or two defining facts per service, and learn the when-to-use-what tables in this guide, and a third of the exam becomes quick points.
The fastest way to lock that recall in is repetition under exam conditions. Work through the AWS Cloud Practitioner mock exams, drill the scenario questions until service selection is automatic, and review every explanation. Do that alongside the Cloud Practitioner study plan, and you’ll walk in confident on the biggest domain of the CLF-C02. For the full roadmap, start with the AWS Cloud Practitioner exam guide for 2026.