EC2 Instance Types

• EC2 Instance types determine the hardware of the host computer used for the instance.
• EC2 Instance types offer different compute, memory & storage capabilities and are grouped in instance families based on these capabilities.
• EC2 provides each instance with a consistent and predictable amount of CPU capacity, regardless of its underlying hardware.
• EC2 dedicates some resources of the host computer, such as CPU, memory, and instance storage, to a particular instance.
• EC2 shares other resources of the host computer, such as the network and the disk subsystem, among instances. If each instance on a host computer tries to use as much of one of these shared resources as possible, each receives an equal share of that resource. However, when a resource is under-utilized, an instance can consume a higher share of that resource while it’s available.
• All current generation instances are built on the AWS Nitro System, a combination of dedicated hardware and a lightweight hypervisor that delivers isolated multi-tenancy, private networking, and fast local storage.

EC2 Instance Naming Convention

• Instance types follow a naming convention: [Family][Generation][Additional capabilities].[Size]
• Example: m7i.xlarge = General Purpose (m), 7th generation, Intel processor, Extra Large size
• Common suffixes:
  • g – AWS Graviton (Arm-based) processor
  • i – Intel processor
  • a – AMD processor
  • d – Local NVMe instance storage
  • n – Network optimized
  • e – Extra storage or memory
  • flex – Flex variant (baseline + burst)

EC2 Instance Types Selection Criteria

• All current generation instances use HVM virtualization exclusively. Paravirtual (PV) is only available on legacy previous-generation instances and is not recommended.
• All EC2 instances run in a VPC. EC2-Classic was fully retired in August 2023.
• Some instances support only EBS volumes, while others support both EBS and Instance store volumes (indicated by “d” suffix, e.g., m7gd, c7gd). Instance store volumes on current generations use NVMe-based SSDs.
• All current generation instances are EBS-optimized by default with dedicated capacity for EBS I/O.
• Some EC2 Instance types can be launched in placement groups to optimize instances for High-Performance Computing (HPC).
• All current generation instances support Enhanced Networking using Elastic Network Adapter (ENA) for significantly higher packet per second (PPS) performance, lower network jitter, and lower latencies.
• All EBS volumes support encryption on current generation instances.
• Processor options: Intel Xeon (6th Gen), AMD EPYC, or AWS Graviton (Arm-based) processors depending on the instance family.

EBS-Optimized

• EBS-optimized instance uses an optimized configuration stack and provides additional, dedicated capacity for EBS I/O.
• EBS-optimized instances enable you to get consistently high performance for the EBS volumes by eliminating contention between EBS I/O and other network traffic from the instance.
• EBS-optimized instances deliver dedicated throughput between Amazon EC2 and EBS, with options between 500 and 400,000 Megabits per second (Mbps) depending on the instance type used.
• When attached to an EBS-optimized instance, General Purpose (SSD) volumes are designed to deliver within 10 percent of their baseline and burst performance 99.9 percent of the time in a given year, and Provisioned IOPS (SSD) volumes are designed to deliver within 10 percent of their provisioned performance 99.9 percent of the time in a given year.
• All current generation instances (5th gen and later) are EBS-optimized by default at no additional cost.

Placement Groups

• EC2 Placement groups determine how the instances are placed on the underlying hardware.
• AWS provides three types of placement groups:
  • Cluster – clusters instances into a low-latency group in a single AZ
  • Partition – spreads instances across logical partitions, ensuring that instances in one partition do not share underlying hardware with instances in other partitions
  • Spread – strictly places a small group of instances across distinct underlying hardware to reduce correlated failures

NOTE – AWS continuously releases new instance types. Refer to the AWS EC2 Instance Types documentation for the latest information.

EC2 Instance Families – Current Generation (2024-2026)

Family	Category	Current Generations	Use Cases
M	General Purpose	M7i, M7g, M7a, M8i, M8g, M9g	Web servers, app servers, gaming, mid-size databases
T	General Purpose (Burstable)	T3, T3a, T4g	Micro-services, dev/test, small databases
C	Compute Optimized	C7i, C7g, C7a, C8i, C8g, C8a	HPC, batch processing, gaming, ML inference
R	Memory Optimized	R7i, R7g, R7a, R8i, R8g	In-memory databases, real-time analytics
X	Memory Intensive	X2gd, X2idn, X8g	SAP HANA, large in-memory databases
I	Storage Optimized (SSD)	I4i, I4g, I7i, I8g	NoSQL databases, OLTP, data warehousing
D	Storage Optimized (HDD)	D3, D3en	Hadoop, data lakes, distributed file systems
G	Accelerated Computing (Graphics)	G5, G6, G6e	ML inference, graphics rendering, game streaming
P	Accelerated Computing (GPU)	P4d, P5, P5e, P5en, P6	Deep learning training, HPC, scientific computing
Hpc	High Performance Computing	Hpc7g, Hpc7a, Hpc6a	Tightly-coupled HPC workloads

AWS Graviton-Based Instances

• AWS Graviton processors are custom-designed by AWS to deliver the best price-performance for cloud workloads.
• Graviton-based instances (suffix “g”) deliver up to 40% better price-performance over comparable x86-based instances.
• Graviton4 (current, 2024) – Powers M8g, C8g, R8g, X8g instances with up to 30% better performance over Graviton3.
• Graviton5 (GA June 2026) – Powers M9g instances with 25% better performance over Graviton4, purpose-built for agentic AI workloads.
• Graviton instances support Linux-based operating systems (Amazon Linux 2/2023, Ubuntu, RHEL, SUSE) and containers.
• Ideal for applications that can run on Arm architecture: web servers, containers, microservices, open-source databases, caching layers, and ML inference.

Flex Instances

• EC2 Flex instances (M7i-flex, C7i-flex, M8i-flex, C8i-flex) are lower-priced variants of their standard counterparts.
• They deliver a baseline of 40% CPU performance and can scale up to full CPU performance 95% of the time.
• Offer up to 19% better price-performance compared to previous generation instances.
• Available in sizes from large to 16xlarge.
• Well suited for: web/application servers, virtual desktops, batch processing, microservices, databases, and enterprise applications.
• Unlike T-series burstable instances, Flex instances do not use a CPU credit system — they simply deliver baseline performance with automatic scaling.

Burstable Performance Instances (T-Series)

• T-series instances (current: T3, T3a, T4g) are designed to provide moderate baseline performance with the capability to burst to significantly higher performance as required.
• Mainly intended for workloads that don’t use the full CPU often or consistently, but occasionally need to burst.
• Well suited for:
  • General-purpose workloads such as web servers, developer environments, remote desktops, and small databases
• Current T-series Instances:
  • T4g – Powered by AWS Graviton2 (Arm-based), up to 40% better price-performance than T3
  • T3 – Intel Xeon processors, Nitro-based
  • T3a – AMD EPYC processors, lower cost alternative to T3
• Features:
  • Launch with HVM AMI only
  • VPC only (EC2-Classic retired)
  • EBS-backed only
  • Available as On-Demand, Reserved, Dedicated Instances (T3/T3a), and Spot Instances
  • Built on AWS Nitro System
  • Support Enhanced Networking with ENA
  • Support Unlimited mode by default (T3/T3a/T4g)
• Unlimited Mode (Default for T3/T3a/T4g)
  • Can sustain high CPU performance for as long as a workload needs it.
  • For most general-purpose workloads, provides ample performance without additional charges.
  • If the instance runs at higher CPU utilization for a prolonged period beyond earned credits, additional charges apply at a flat rate per vCPU-hour.

CPU Credits

• CPU Credits provide the performance of a full CPU core for one minute.
• T-series instances provide a baseline level of CPU performance, while CPU credits govern the ability to burst above the baseline level.
• One CPU credit is equal to one vCPU running at 100% utilization for one minute. For e.g., One vCPU running at 100% for One min OR One vCPU running @ 50% for 2 mins OR Two vCPU running @ 25% for 2 mins.
• Each instance continuously receives a set rate of CPU credits per hour, depending on instance size.
• Each instance accumulates CPU credits when it uses fewer CPU resources than its allowed baseline performance levels.
• Maximum earned credit balance for an instance is equal to the number of CPU credits received per hour times 24 hours.
• CPU credit balance is available for a period of 24 hours; it expires 24 hours after they were earned.
• CPU credits cease to persist between an instance stop-start. However, after the start, the instance receives initial CPU credits again.
• In Standard mode, when the credit balance is completely exhausted, the instance will perform at its baseline performance.
• In Unlimited mode (default for T3/T3a/T4g), the instance can burst beyond earned credits and surplus credits are charged.

C7i/C8i Instances (Compute Optimized – Current Generation)

• Compute-optimized instances are ideal for compute-bound applications that benefit from high-performance processors.
• Current generation compute-optimized:
  • C8i / C8i-flex (2025) – Custom Intel Xeon 6 processors, up to 20% better performance than C7i
  • C8g / C8gn (2025) – Graviton4, up to 30% better performance than C7g; C8gn offers up to 600 Gbps network bandwidth
  • C8a (2025) – AMD EPYC, up to 57% faster for Java workloads than C7a
  • C7i / C7i-flex – 4th Gen Intel Xeon Scalable (Sapphire Rapids)
  • C7g / C7gn – Graviton3 processors
  • C7a – AMD EPYC (Genoa) processors
• Well suited for:
  • Batch processing workloads
  • Media transcoding
  • High-performance web servers
  • High-performance computing (HPC)
  • Scientific modeling and machine learning inference
  • Dedicated gaming servers and ad serving engines
• Features:
  • EBS-optimized by default
  • Enhanced Networking with ENA (up to 600 Gbps for C8gn)
  • Can be launched in placement groups
  • Built on AWS Nitro System
  • Requires 64-bit HVM AMI

G5/G6 Instances (Accelerated Computing – Graphics)

• GPU instances provide high parallel processing capability for graphics and ML inference workloads.
• Current generation:
  • G6 / G6e (2024) – NVIDIA L4 GPUs (up to 8), ideal for ML inference and graphics workloads
  • G5 – NVIDIA A10G GPUs (up to 8), for graphics-intensive applications and ML inference
• Well suited for:
  • Machine learning inference
  • Graphics rendering and game streaming
  • Video transcoding with hardware acceleration
  • Remote visualization workstations
• For deep learning training, use P-series instances:
  • P5 / P5en – NVIDIA H100/H200 Tensor Core GPUs for large-scale training
  • P4d / P4de – NVIDIA A100 GPUs
• Features:
  • Built on AWS Nitro System
  • Requires HVM AMI with NVIDIA drivers installed
  • Support Enhanced Networking with ENA
  • Support Elastic Fabric Adapter (EFA) for GPU-to-GPU communication

I4i/I7i/I8g Instances (Storage Optimized – SSD)

• Storage-optimized I-series instances are designed to deliver high random I/O operations per second (IOPS) to applications.
• Current generation:
  • I8g (2024) – Graviton4 + 3rd Gen Nitro SSDs, up to 65% better storage performance per TB vs I4g
  • I7i (2025) – Intel Xeon + 3rd Gen Nitro SSDs, up to 50% better storage performance vs I4i, up to 45TB NVMe
  • I4i – Intel Xeon (Ice Lake) + Nitro SSDs, up to 30TB NVMe storage
  • I4g / Im4gn / Is4gen – Graviton2-based storage optimized
• Well suited for:
  • NoSQL databases (Cassandra, MongoDB, DynamoDB-compatible)
  • In-memory databases
  • Online transaction processing (OLTP) systems
  • Real-time analytics and data warehousing
• Features:
  • NVMe-based SSD instance storage with always-on encryption
  • Built on AWS Nitro System
  • Enhanced Networking with ENA
  • Can be launched in placement groups
  • EBS-optimized by default

D3/D3en Instances (Storage Optimized – HDD)

• D3/D3en instances are designed for workloads with very high storage density and that require high sequential read/write access to very large data sets on local storage.
• Current generation:
  • D3 – 30% higher processor performance, 2.5x higher networking, 45% higher disk throughput compared to D2
  • D3en – Up to 336TB of HDD storage, optimized for lowest cost per TB of storage
• Well suited for:
  • Massive parallel processing (MPP) data warehouse
  • Hadoop/Spark distributed computing and data lakes
  • Log or data processing applications
  • Distributed file systems
• Features:
  • Primary data storage is HDD-based instance storage
  • EBS-optimized by default
  • Enhanced Networking with ENA
  • Can be clustered in a placement group
  • Built on AWS Nitro System

AWS Nitro System

• The AWS Nitro System is the underlying platform for all current generation EC2 instances.
• It offloads virtualization, storage, and networking functions to dedicated hardware and software.
• Benefits:
  • Nearly all CPU resources devoted to customer workloads
  • Enhanced security with hardware-based isolation
  • Higher network performance (up to 600 Gbps)
  • Higher EBS performance (up to 400 Gbps)
  • Bare metal instances (no hypervisor overhead)
• Nitro components: Nitro Cards (VPC, EBS, local storage), Nitro Security Chip, Nitro Hypervisor.
• 6th generation Nitro Cards (2026) power the latest C8, M8, R8 instances.

AWS Certification Exam Practice Questions

• Questions are collected from Internet and the answers are marked as per my knowledge and understanding (which might differ with yours).
• AWS services are updated everyday and both the answers and questions might be outdated soon, so research accordingly.
• AWS exam questions are not updated to keep up the pace with AWS updates, so even if the underlying feature has changed the question might not be updated
• Open to further feedback, discussion and correction.

1. Which of the following instance types are available as Amazon EBS-backed only? Choose 2 answers
   1. General purpose T2
   2. General purpose M3
   3. Compute-optimized C4
   4. Compute-optimized C3
   5. Storage-optimized I2
2. A t2.medium EC2 instance type must be launched with what type of Amazon Machine Image (AMI)?
   1. An Instance store Hardware Virtual Machine AMI
   2. An Instance store Paravirtual AMI
   3. An Amazon EBS-backed Hardware Virtual Machine AMI
   4. An Amazon EBS-backed Paravirtual AMI
3. You have identified network throughput as a bottleneck on your m1.small EC2 instance when uploading data into Amazon S3 in the same region. How do you remedy this situation?
   1. Add an additional ENI
   2. Change to a larger instance
   3. Use DirectConnect between EC2 and S3
   4. Use EBS PIOPS on the local volume

   [Note: m1.small is a previous generation instance. Current recommendation would be to migrate to a current-gen instance like M7i or T3 for better network performance.]

4. You are using an m1.small EC2 Instance with one 300 GB EBS volume to host a relational database. You determined that write throughput to the database needs to be increased. Which of the following approaches can help achieve this? Choose 2 answers
   1. Use an array of EBS volumes (Striping to increase throughput)
   2. Enable Multi-AZ mode
   3. Place the instance in an Auto Scaling Groups
   4. Add an EBS volume and place into RAID 5 (RAID 5 is not recommended as it provides parity and EBS volumes are already replicated across multiple servers in an Availability Zone for availability and durability, so AWS recommends striping for performance rather than durability)
   5. Increase the size of the EC2 Instance
   6. Put the database behind an Elastic Load Balancer
5. You are tasked with setting up a cluster of EC2 Instances for a NoSQL database. The database requires random read IO disk performance up to a 100,000 IOPS at 4KB block size per node. Which of the following EC2 instances will perform the best for this workload?
   1. A High-Memory Quadruple Extra Large (m2.4xlarge) with EBS-Optimized set to true and a PIOPs EBS volume
   2. A Cluster Compute Eight Extra Large (cc2.8xlarge) using instance storage
   3. High I/O Quadruple Extra Large (hi1.4xlarge) using instance storage
   4. A Cluster GPU Quadruple Extra Large (cg1.4xlarge) using four separate 4000 PIOPS EBS volumes in a RAID 0 configuration

   [Note: This is a legacy question. For current generation, I4i or I7i instances would be the optimal choice for high IOPS NoSQL workloads, offering hundreds of thousands of IOPS with NVMe SSDs.]
6. A t2.medium EC2 instance type must be launched with what type of Amazon Machine Image (AMI)?
   1. An Instance store Hardware Virtual Machine AMI
   2. An Instance store Paravirtual AMI
   3. An Amazon EBS-backed Hardware Virtual Machine AMI
   4. An Amazon EBS-backed Paravirtual AMI
7. You are implementing a URL whitelisting system for a company that wants to restrict outbound HTTPS connections to specific domains from their EC2-hosted applications. You deploy a single EC2 instance running proxy software and configure it to accept traffic from all subnets and EC2 instances in the VPC. After a few days you notice that some machines are failing to successfully download some updates. What might be happening? (Choose 2 answers) [PROFESSIONAL]
   1. You are running the proxy on an undersized EC2 instance type so network throughput is not sufficient for all instances to download their updates in time.
   2. You have not allocated enough storage to the EC2 instance running the proxy so the network buffer is filling up causing some requests to fail
   3. You are running the proxy in a public subnet but have not allocated enough EIPs to support the needed network throughput through the Internet Gateway (IGW)
   4. You are running the proxy on a sufficiently-sized EC2 instance in a private subnet and its network throughput is being throttled by a NAT running on an undersized EC2 instance
   5. The route table for the subnets containing the affected EC2 instances is not configured to direct network traffic for the software update locations to the proxy
8. You have been asked to design the storage layer for an application. The application requires disk performance of at least 100,000 IOPS. The storage layer must be able to survive the loss of an individual disk, EC2 instance, or Availability Zone without any data loss. The volume must have a capacity of at least 3TB. Which design will meet these objectives? [PROFESSIONAL]
   1. Instantiate an i2.8xlarge instance in us-east-1a. Create a RAID 0 volume using the four 800GB SSD ephemeral disks provided with the instance. Provision 3×1 TB EBS volumes, attach them and configure them as a second RAID 0 volume. Configure synchronous, block-level replication from the ephemeral backed volume to the EBS-backed volume. (Same AZ will not survive the AZ loss)
   2. Instantiate an i2.8xlarge instance in us-east-1a. Create a RAID 0 volume using the four 800GB SSD ephemeral disks provided with the instance. Configure synchronous block-level replication to an identically configured instance in us-east-1b.
   3. Instantiate a c3.8xlarge instance in us-east-1. Provision an AWS Storage Gateway and configure it for 3 TB of storage and 100,000 IOPS. Attach the volume to the instance. (Need synchronous replication to prevent any data loss)
   4. Instantiate a c3.8xlarge instance in us-east-1. Provision 4x1TB EBS volumes, attach them and configure them as a single RAID 5 volume. Ensure that EBS snapshots are performed every 15 minutes. (RAID 5 not recommended by AWS and Need synchronous replication to prevent any data loss)
   5. Instantiate a c3.8xlarge instance in us-east-1. Provision 3x1TB EBS volumes, attach them and configure them as a single RAID 0 volume. Ensure that EBS snapshots are performed every 15 minutes. (Need synchronous replication to prevent any data loss)

   [Note: This is a legacy question using previous-gen instances (i2, c3). For current architecture, I7i instances with cross-AZ replication or io2 Block Express volumes with Multi-Attach would be considered.]

9. [NEW] A company wants to deploy a general-purpose web application with unpredictable traffic patterns. They want the best price-performance and the application runs on Linux with open-source software. Which instance type provides the best option?
   1. M7i.large
   2. T4g.large
   3. C7i.large
   4. T3.large

   [T4g offers the best price-performance for burstable workloads with open-source Linux applications due to Graviton2 Arm-based processors.]

10. [NEW] A company needs to run a high-performance NoSQL database that requires consistent sub-millisecond latency and at least 100,000 random read IOPS from local storage. Which current-generation instance family is MOST suitable?
    1. D3en
    2. M7i
    3. I4i
    4. R7g

    [I4i instances use AWS Nitro NVMe SSDs optimized for high random IOPS with consistent low latency, ideal for NoSQL databases.]
11. [NEW] Which of the following are benefits of AWS Graviton-based instances? (Choose 3 answers)
    1. Up to 40% better price-performance over comparable x86 instances
    2. Support for Windows Server operating system
    3. Lower energy consumption and better sustainability
    4. Support for Linux-based operating systems and containers
    5. Support for PV (paravirtual) AMIs
12. [NEW] Which statement about EC2 Flex instances (e.g., M7i-flex, C7i-flex) is correct?
    1. They use a CPU credit system similar to T2 instances
    2. They are only available for Graviton-based instances
    3. They deliver a baseline of 40% CPU performance and can scale up to full performance 95% of the time
    4. They are limited to small and medium instance sizes only
13. [NEW] All current generation EC2 instances share which of the following characteristics? (Choose 3 answers)
    1. Built on the AWS Nitro System
    2. Support both HVM and PV virtualization
    3. EBS-optimized by default
    4. Support Enhanced Networking with ENA
    5. Include local instance storage

References

• EC2 Instance Types
• EC2 Instance Types Specifications
• EC2 User Guide – Instance Types
• AWS Graviton Processors
• AWS Nitro System
• Previous Generation Instances
• Burstable Performance Instances