AWS Regions and Availability Zones: the Simplest Explanation you Will Ever Find Around

(Update) If you are deploying services on AWS, you’ll want to have a clear understanding of each of these components, how they are linked, and how you can use them within your solution to YOUR maximum benefit. We take a closer look at them in this post AWS Global Infrastructure: Availability Zones, Regions, Edge Locations, Regional Edge Caches


When it comes to Amazon Web Services, there are two concepts that are extremely important and spanning across all the services, and that you simply can’t help but be aware of: Regions and Availability Zones. Both of them associate with most of the AWS stuff, and mastering them is crucial to get the best out of them. Nevertheless, many users underrate their importance or even completely ignore the concepts at the base of it. In this post, I’ll try to give you the simplest explanation ever of what are Regions and Availability Zones, and everything you should know to use them at your advantage.

First things first: Regions

Amazon EC2 is hosted in multiple locations all over the world.
It’s quite straightforward that resources geographically close to the client are served faster, so you can immediately get the rationale of creating so many regions all over the world: getting resources closer to who asks them. Right now, AWS has about 10 regions available, three of them in the US and the others spread over Europe, Asia, Pacific, and South America, but stay assured that more of them will be opened in the future.

For many of the AWS services, you will be asked in which region you want to deploy your resources. For example, if you launch an EC2 instance, you will be asked in which region to host it. Each region is totally isolated from the others, and they can talk only via the Internet. Actually, Regions are so isolated that when you view your resources, you’ll only see the resources tied to the region you’ve specified: AWS doesn’t replicate resources across regions automatically.

Splitting Regions in parts: Availability Zones

An Availability Zone is an isolated location inside a region. Each region is made up of several Availability Zones. Each Availability Zones belong to a single region. Also, each AZ (as AWS expert commonly call Availability Zones) is isolated, but the AZs in a region are connected through low-latency links. This picture from the AWS documentation probably explains the whole concept better than a thousand words:
Image showing an example of how AWS Regions and Availability Zones are distributed

So, we have 3 different scopes here: the whole AWS, Regions, and AZ. According to the AWS service, and specifically for EC2, each resource can belong to one of them. For example, IAM is global, AMIs are regional, instances belong to AZs, and so on.

Taking advantage of the Availability Zones

There are several reasons why a good strategy with regard to AZs might come in handy in several different situations. Just to cite some of the most common use cases, if you distribute your instances across multiple Availability Zones and one instance fails, you can design your application so that an instance in another Availability Zone can handle requests. A sort of emergency load balancer without using an actual load balancer.

Also, you can mix it with Elastic IP addresses to mask the failure of an instance in one Availability Zone: enough you remap the address to an instance in another Availability Zone. Not the best strategy in the long term, but enough quick-and-dirty to make your day in certain situations. Beware though: Amazon maps AZs independently for each account, so your us-east-1a might not be the same location as someone else’s us-east-1a, and you will never know what the actual mapping is.

One last bit of complexity: endpoints

There is one more concept around, and one that I have seen a lot of people getting lost about: endpoints. Long story short: there are several ways to access a service, a region and/or availability zones, and they are called endpoints. In other words, they are URLs acting as an entry point for a web service. Again, they aim to reduce even further the latency of your applications. Not all the AWS services support endpoints though. As I told you already, IAM is a typical example of a global service, and it’s the only endpoint is https://iam.amazonaws.com.

On the other end, stuff like DynamoDB might be accessed through URLs like https://dynamodb.eu-west-1.amazonaws.com. Not a totally new concept, then, neither yet another partition of the AWS resources: endpoints are just the door entrance to global, regional and AZ-related resources in the AWS world. Just as simple as that.

Avatar

Written by

Andrea Colangelo

Software Engineer with a solid focus on QA and an extensive experience in ICT. Above all, Andrea has a very strong interest in Free and Open Source Software, and he is a Debian and Ubuntu Developer since years. Non-tech interests include: Rugby, Jazz music and Cooking.


Related Posts

Avatar
Stuart Scott
— October 16, 2019

AWS Security: Bastion Host, NAT instances and VPC Peering

Effective security requires close control over your data and resources. Bastion hosts, NAT instances, and VPC peering can help you secure your AWS infrastructure. Welcome to part four of my AWS Security overview. In part three, we looked at network security at the subnet level. This ti...

Read more
  • AWS
Avatar
Sudhi Seshachala
— October 9, 2019

Top 13 Amazon Virtual Private Cloud (VPC) Best Practices

Amazon Virtual Private Cloud (VPC) brings a host of advantages to the table, including static private IP addresses, Elastic Network Interfaces, secure bastion host setup, DHCP options, Advanced Network Access Control, predictable internal IP ranges, VPN connectivity, movement of interna...

Read more
  • AWS
  • best practices
  • VPC
Avatar
Stuart Scott
— October 2, 2019

Big Changes to the AWS Certification Exams

With AWS re:Invent 2019 just around the corner, we can expect some early announcements to trickle through with upcoming features and services. However, AWS has just announced some big changes to their certification exams. So what’s changing and what’s new? There is a brand NEW ...

Read more
  • AWS
  • Certifications
Alisha Reyes
Alisha Reyes
— October 1, 2019

New on Cloud Academy: ITIL® 4, Microsoft 365 Tenant, Jenkins, TOGAF® 9.1, and more

At Cloud Academy, we're always striving to make improvements to our training platform. Based on your feedback, we released some new features to help make it easier for you to continue studying. These new features allow you to: Remove content from “Continue Studying” section Disc...

Read more
  • AWS
  • Azure
  • Google Cloud Platform
  • ITIL® 4
  • Jenkins
  • Microsoft 365 Tenant
  • New content
  • Product Feature
  • Python programming
  • TOGAF® 9.1
Avatar
Stuart Scott
— September 27, 2019

AWS Security Groups: Instance Level Security

Instance security requires that you fully understand AWS security groups, along with patching responsibility, key pairs, and various tenancy options. As a precursor to this post, you should have a thorough understanding of the AWS Shared Responsibility Model before moving onto discussi...

Read more
  • AWS
  • instance security
  • Security
  • security groups
Avatar
Jeremy Cook
— September 17, 2019

Cloud Migration Risks & Benefits

If you’re like most businesses, you already have at least one workload running in the cloud. However, that doesn’t mean that cloud migration is right for everyone. While cloud environments are generally scalable, reliable, and highly available, those won’t be the only considerations dri...

Read more
  • AWS
  • Azure
  • Cloud Migration
Joe Nemer
Joe Nemer
— September 12, 2019

Real-Time Application Monitoring with Amazon Kinesis

Amazon Kinesis is a real-time data streaming service that makes it easy to collect, process, and analyze data so you can get quick insights and react as fast as possible to new information.  With Amazon Kinesis you can ingest real-time data such as application logs, website clickstre...

Read more
  • amazon kinesis
  • AWS
  • Stream Analytics
  • Streaming data
Joe Nemer
Joe Nemer
— September 6, 2019

Google Cloud Functions vs. AWS Lambda: The Fight for Serverless Cloud Domination

Serverless computing: What is it and why is it important? A quick background The general concept of serverless computing was introduced to the market by Amazon Web Services (AWS) around 2014 with the release of AWS Lambda. As we know, cloud computing has made it possible for users to ...

Read more
  • AWS
  • Azure
  • Google Cloud Platform
Joe Nemer
Joe Nemer
— September 3, 2019

Google Vision vs. Amazon Rekognition: A Vendor-Neutral Comparison

Google Cloud Vision and Amazon Rekognition offer a broad spectrum of solutions, some of which are comparable in terms of functional details, quality, performance, and costs. This post is a fact-based comparative analysis on Google Vision vs. Amazon Rekognition and will focus on the tech...

Read more
  • Amazon Rekognition
  • AWS
  • Google Cloud Platform
  • Google Vision
Alisha Reyes
Alisha Reyes
— August 30, 2019

New on Cloud Academy: CISSP, AWS, Azure, & DevOps Labs, Python for Beginners, and more…

As Hurricane Dorian intensifies, it looks like Floridians across the entire state might have to hunker down for another big one. If you've gone through a hurricane, you know that preparing for one is no joke. You'll need a survival kit with plenty of water, flashlights, batteries, and n...

Read more
  • AWS
  • Azure
  • Google Cloud Platform
  • New content
  • Product Feature
  • Python programming
Joe Nemer
Joe Nemer
— August 27, 2019

Amazon Route 53: Why You Should Consider DNS Migration

What Amazon Route 53 brings to the DNS table Amazon Route 53 is a highly available and scalable Domain Name System (DNS) service offered by AWS. It is named by the TCP or UDP port 53, which is where DNS server requests are addressed. Like any DNS service, Route 53 handles domain regist...

Read more
  • Amazon
  • AWS
  • Cloud Migration
  • DNS
  • Route 53
Alisha Reyes
Alisha Reyes
— August 22, 2019

How to Unlock Complimentary Access to Cloud Academy

Are you looking to get trained or certified on AWS, Azure, Google Cloud Platform, DevOps, Cloud Security, Python, Java, or another technical skill? Then you'll want to mark your calendars for August 23, 2019. Starting Friday at 12:00 a.m. PDT (3:00 a.m. EDT), Cloud Academy is offering c...

Read more
  • AWS
  • Azure
  • cloud academy content
  • complimentary access
  • GCP
  • on the house