Route 53 fundamentals — AWS Solutions Architect Associate Exam.

Chapter 10: Route 53 fundamentals for the AWS SAA C03 Certification Exam.

In this chapter, we will study how AWS Route 53 works and all its main features, like the different Routing Policies we can use. These are the key concepts that we are going to review:

1. Route 53 Introduction
2. Supported DNS record types
3. Hosted Zones
4. Routing Policies

Route 53 for the AWS Solutions Architect Associate Certification.

Remember that all the chapters from the course can be found in the following link.

AWS ROUTE 53 INTRODUCTION

At its most basic, a Domain Name System (DNS) is a directory of names that match IP addresses. Route 53 is AWS’s highly available and scalable cloud DNS web service.

It also has a service called Domain Registrar. When you want to get or register a new domain name, for example, the domain myrealcode.com part of the URL https://myrealcode.com/, you can register it with Amazon Route 53 Domain Registrar. You can also transfer the registration for existing domains from other registrars to Route 53 or transfer the registration for domains you register with Route 53 to another registrar. If you buy your domain on 3rd party website, you can still use Route53.

How to register a domain using AWS Route 53.

As we saw with the Load Balancers, Health Checks can also be placed on Route 53.

SUPPORTED DNS RECORD TYPES

• A records → Route traffic to a resource, such as a web server, using an IPv4 address. Route to 104.198.14.52, for example.

How Route 53 works.

• AAAA records → Route traffic to a resource, such as a web server, using an IPv6 address. Route to 2001:0db8:85a3:0:0:8a2e:0370:7334 for example.
• CNAME → Maps DNS queries for the name of the current record, such as app.myrealcode.com, to another domain (myrealcode.com or myrealcode.net) or subdomain (app2.myrealcode.com).
  It does not allow you to create a CNAME record for the top node of a DNS namespace, also known as the zone apex. For example, if you register the DNS name myrealcode.com, the zone apex is myrealcode.com. You cannot create a CNAME record for myrealcode.com, but you can create CNAME records for app.myrealcode.com.
• Alias records → It Allows you to route queries to selected AWS resources. Aliases are similar in some ways to the CNAME record type; however, you can create an alias for the zone apex. This is important; you could make an alias for myrealcode.com. They are free. You can specify (we’ll see these services soon) CloudFront Distributions, Elastic Beanstalk Environments, S3 Websites, Network Load Balancers, API Gateways…

HOSTED ZONES

A hosted zone is a container for records containing information about how you want to route traffic for a specific domain and its subdomains. So basically, with the hosted zone, we will establish the rules. Every time we buy a domain using Domain Registrar, a Hosted Zone will be created and cost 0.50$ per month per Hosted Zone. In the following example, I would have to pay $1 per month, as we have two hosted zones, and the domain registration, which is around $12 per year per website.

Types of hosted zones:

• Public hosted zones → Contain records that specify how you want to route traffic on the internet.
• Private hosted zones → Contain records that specify how you want to route traffic in an Amazon VPC.

ROUTING POLICIES

When you create a record, you choose a routing policy, which determines how Amazon Route 53 responds to queries. For example, imagine an application with several instances. We can return the IP of one or the other based on different parameters, such as the user’s location, to make navigation faster. Let’s take a look at the different Routing Policies:

• Simple routing policy → Used when redirecting to a single resource. If Route 53 returns more than one result, the client access one of those randomly.

Route 53 Simply Routing Policy.

• Weighted routing policy → Used when you want to route traffic to multiple resources in proportions that you specify. For example, we could redirect 20% of the users to the new application version to test it.

Route 53 Weighted Routing Policy.

• Latency routing policy → Used when you want to route traffic to the Region that provides the best latency to the user. It doesn’t redirect to the closest one but to the one with the best latency, as we can see with the user in the bottom right of this image:

Route 53 Latency Routing Policy.

• Failover routing policy → Used when you want to route traffic to a different instance in case the primary one fails. The health check is mandatory.

Route 53 Failover Routing Policy.

• Geolocation routing policy → Used when you want to route traffic based on the location of your users. For example, you could say that all the users from America are routed to this specific IP.

Route 53 Geolocation Routing Policy.

• Geoproximity routing policy → Used when you want to route traffic based on the location of your resources.

• Multivalue answer routing policy → Used when you want Route 53 to respond to DNS queries with up to eight healthy records selected randomly. You can add health checks; this is the main difference with the Simple routing policy.
• IP-based routing policy (NEW) → It enables you to route traffic to resources of your domain based on the client subnet. You define the CIDR blocks that represent your client IP network ranges and map those CIDR blocks to locations.

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