DNSRouting

When you think about the cloud, it’s easy to get lost in the vastness of it all, servers, data centers, networks, and more. But at the core of it, there’s a simple idea: making sure that when someone types a website name into their browser, they get where they need to go as quickly and reliably as possible. That’s where AWS Route 53 comes into play. Route 53 is a powerful tool that Amazon Web Services provides to help manage how internet traffic gets directed to your online resources, like web servers or applications.

Now, one of the things that makes Route 53 special is its range of Routing Policies. These policies let you control how traffic is distributed to your resources based on different criteria. Let’s break these down in a way that’s easy to understand, and along the way, I’ll show you how each can be useful in real-life situations.

Simple Routing Policy

Let’s start with the Simple Routing Policy. This one lives up to its name, it routes traffic to a single resource. Imagine you’ve got a website, and it’s running on a single server. You don’t need anything fancy here; you want all the traffic to your domain, say www.mysimplewebsite.com, to go straight to that server. Simple Routing is your go-to. It’s like directing all the cars on a road to a single destination without any detours.

Failover Routing Policy

But what happens when things don’t go as planned? Servers can go down, there’s no way around it. This is where the Failover Routing Policy shines. Picture this: you’ve got a primary server that handles all your traffic. But, just in case that server fails, you’ve set up a backup server in another location. Failover Routing is like having a backup route on your GPS; if the main road is blocked, it automatically takes you down the secondary road. Your users won’t even notice the switch, they’ll just keep on going as if nothing happened.

Geolocation Routing Policy

Next up is the Geolocation Routing Policy. This one’s pretty cool because it lets you route traffic based on where your users are physically located. Say you run a global business and you want users in Japan to access your website in Japanese and users in Germany to get the content in German. With Geolocation Routing, Route 53 checks where the DNS query is coming from and sends users to the server that best fits their location. It’s like having custom-tailored suits for your website visitors, giving them exactly what they need based on where they are.

Geoproximity Routing Policy

Now, if Geolocation is like tailoring content to where users are, Geoproximity Routing Policy takes it a step further by letting you fine-tune things even more. This policy allows you to route traffic not just based on location, but also based on the physical distance between the user and your resources. Plus, you can introduce a bias, maybe you want to favor one location over another for strategic reasons. Imagine you’re running servers in New York and London, but you want to make sure that even though a user in Paris is closer to London, they sometimes get routed to New York because you have more resources available there. Geoproximity Routing lets you do just that, like tweaking the dials on a soundboard to get the perfect mix.

Latency-Based Routing Policy

Ever notice how some websites just load faster than others? A lot of that has to do with latency, the time it takes for data to travel between the server and your device. With the Latency-Based Routing Policy, Route 53 directs users to the resource that will respond the quickest. This is especially useful if you’ve got servers spread out across the globe. If a user in Sydney accesses your site, Latency-Based Routing will send them to the nearest server in, say, Singapore, rather than making them wait for a response from a server in the United States. It’s like choosing the shortest line at the grocery store to get your shopping done faster.

Multivalue Answer Routing Policy

The Multivalue Answer Routing Policy is where things get interesting. It’s kind of like a basic load balancer. Route 53 can return several IP addresses (up to eight to be exact) in response to a single DNS query, distributing traffic among multiple resources. If one of those resources fails, it gets removed from the list, so your users only get directed to healthy resources. Think of it as having multiple checkout lines open at a store; if one line gets too long or closes down, customers are directed to the next available line.

Weighted Routing Policy

Finally, there’s the Weighted Routing Policy, which is all about control. Imagine you’re testing a new feature on your website. You don’t want to send all your users to the new version right away, instead, you want to direct a small percentage of traffic to it while the rest still go to the old version. With Weighted Routing, you assign a “weight” to each version, controlling how much traffic goes where. It’s like controlling the flow of water with a series of valves; you can adjust them to let more or less water (or in this case, traffic) flow through each pipe.

Wrapping It All Up

So there you have it, AWS Route 53’s Routing Policies in a nutshell. Whether you’re running a simple blog or a complex global application, these policies give you the tools to manage how your users connect to your resources. They help you make sure that traffic gets where it needs to go, efficiently and reliably. And the best part? You don’t need to be a DNS expert to start using them. Just think about what you need, reliability, speed, localized content, or a mix of everything and there’s a routing policy that can make it happen.

In the end, understanding these policies isn’t just about learning some technical details; it’s about gaining the power to shape how your online presence performs in the real world.

Imagine Amazon Route 53 as a city’s traffic control system that directs cars (internet traffic) to different streets (servers or resources) based on traffic conditions and road health (the health and configuration of your AWS resources).

Active-Active Failover

In an active-active scenario, you have two streets leading to your destination (your website or application), and both are open to traffic all the time. If one street gets blocked (a server fails), traffic simply continues flowing through the other street. This is useful when you want to balance the load between two resources that are always available.

Active-active failover gives you access to all resources during normal operation. In this example, both region 1 and region 2 are active all the time. When a resource becomes unavailable, Route 53 can detect that it’s unhealthy and stop including it when responding to queries.

Active-Passive Failover

In active-passive failover, you have one main street that you prefer all traffic to use (the primary resource) and a secondary street that’s only used if the main one is blocked (the secondary resource is activated only if the primary fails). This method is useful when you have a preferred resource to handle requests but need a backup in case it fails.

Use an active-passive failover configuration when you want a primary resource or group of resources to be available the majority of the time and you want a secondary resource or group of resources to be on standby in case all the primary resources become unavailable.

Configuring Active-Passive Failover with One Primary and One Secondary Resource

This approach is like having one big street and one small street. You use the big street whenever possible because it can handle more traffic or get you to your destination more directly. You only use the small street if there’s construction or a blockage on the big street.

Configuring Active-Passive Failover with Multiple Primary and Secondary Resources

Now imagine you have several big streets and several small streets. All the big ones are your preferred options, and all the small ones are your backup options. Depending on how many big streets are available, you’ll direct traffic to them before considering using the small ones.

Configuring Active-Passive Failover with Weighted Records

This is like having multiple streets leading to your destination, but you give each street a “weight” based on how often you want it used. Some streets (resources) are preferred more than others, and that preference is adjusted by weight. You still have a backup street for when your preferred options aren’t available.

Evaluating Target Health

“Evaluate Target Health” is like having traffic sensors that instantly tell you if a street is blocked. If you’re routing traffic to AWS resources for which you can create alias records, you don’t need to set up separate health checks for those resources. Instead, you enable “Evaluate Target Health” on your alias records, and Route 53 will automatically check the health of those resources. This simplifies setup and keeps your traffic flowing to streets (resources) that are open and healthy without needing additional health configurations.

In short, Amazon Route 53 offers a powerful set of tools that you can use to manage the availability and resilience of your applications through a variety of ways to apply failover configurations. Implementation of such knowledge into the practice of failover strategy will result in keeping your application up and available for the users in cases when any kind of resource fails or gets a downtime outage.

An Easy Introduction to Route 53 Routing Policies