What is AWS Route 53?

Key takeaways:

• AWS Route 53 is a scalable and highly available DNS web service.

• The 53 in Route 53 refers to the standard TCP/UDP port for DNS services.

• It offers domain registration, hosting, DNS routing, and health checks.

• Health checks can monitor endpoint availability and redirect traffic based on results.

• Domain registration involves creating a hosted zone and assigning name servers.

• Public hosted zones allow DNS access from the internet, while private zones restrict it to Amazon VPCs.

• Split-view zones enable different DNS records for internal and external users.

• Route 53 supports various routing policies, like simple, failover, weighted, and latency-based routing.

• Health checks can be enhanced with CloudWatch alarms and calculated health checks for grouped resources.

• Routing policies control how traffic is routed to different endpoints, optimizing performance and availability.

AWS Route 53 is a scalable and highly available Domain Name System (DNS) web service provided by Amazon Web Services (AWS). Route 53 helps us manage domain names. The “53” in Route 53 refers to the TCP and UDP port number 53, a standard port for DNS services. Route 53 operates on an infrastructure as a service (IaaS) model. Route 53 is a globally resilient service. The name servers are distributed globally and have the same datasets across all the servers. So, even if a region is affected by outages, Route 53 will still function.

The services that Route 53 provides are:

• Domain registration: We can register new domain names directly through Route 53. AWS acts as a domain registrar, and we can manage the entire domain life cycle from within the AWS Management Console.

• Domain hosting: We can use Route 53 to host a domain. Route 53 allocates the servers responsible for DNS resolution and redirects traffic to the endpoints.

• DNS routing: We can use the Routing policies offered by Route 53 to manage the traffic flow to the endpoints. Route 53 provides a wide range of routing policies that can be used in different scenarios.

• Health checks: We can use Route 53 to monitor the health and performance of our applications and endpoints. It provides health checks that can be configured to check the availability and functionality of web applications, email servers, and other resources.

Let’s have a look at how domain registration works on Route 53.

How does domain registration work in Route 53?

Route 53 collaborates with top-level domain registries such as .com, .io, .net, and .org. When a domain is registered using Route 53, it first checks with the registry for that top-level domain if it is available. Route 53 then automatically makes itself the DNS service for the domain by doing the following:

1. Route 53 creates a hosted zoneA hosted zone in Route 53 is like a digital folder where we store all the important details about a website’s address, known as DNS records. These records specify how to direct visitors to the right web pages and handle email messages. Essentially, a hosted zone is analogous to a traditional DNS zone file. It’s a convenient way to ensure visitors reach the correct destination when accessing a website and that email messages are delivered to the right recipients. with the same name as the domain.

2. Route 53 allocates a set of four name servers to the newly created hosted zone. When users attempt to access the registered domain through their web browsers, these name servers direct the browser to the appropriate resources, such as a web server or other services.

3. Route 53 retrieves the name servers associated with the hosted zone and links them with the registered domain to ensure seamless DNS resolution.

4. As the registration process concludes, Route 53 forwards the domain information to the registrar responsible for managing domain registrations. 

5. The registrar then forwards the domain information to the corresponding registry, which maintains a database of domain registrations for specific top-level domains, such as .com. Additionally, certain details may be included in the public WHOIS database for transparency and accessibility.

The illustration below shows how a domain is registered using Route 53:

Hosted zones in Route 53

DNS hosting manages a domain’s Domain Name System (DNS) records. DNS is a critical part of the internet’s infrastructure, as it translates human-readable domain names (like www.example.com) into IP addresses (like 192.0.2.1) that computers use to identify each other on the network. A hosted zone in Route 53 is like a digital folder where we store all the important details about a website’s address, known as DNS records. These records specify how to direct visitors to the right web pages and handle email messages. Essentially, a hosted zone is analogous to a traditional DNS zone file. It’s a convenient way to ensure visitors reach the correct destination when accessing a website and that email messages are delivered to the right recipients.

For the hosting configurations, Route 53 offers us the following hosting options:

• Public hosted zone: In public hosted zones, the zone file is hosted on public name servers, making it accessible from both the public internet and VPCs utilizing the Route 53 resolver. When a public hosted zone is created, Route 53 assigns four public name servers to host the zone files.

• Private hosted zone: In private hosted zones, the zone file is hosted on private name servers, making it accessible only within one or more specified Amazon VPCs. This ensures that the DNS records are not exposed to the public internet, enhancing security and privacy for internal resources. When a private hosted zone is created, Route 53 allocates private name servers within the specified VPCs to manage and resolve DNS queries internally.

• Split-view zone: Split-view zones (or split-horizon DNS) involve hosting different zone files on public and private name servers. This setup allows the same domain to have different DNS records based on where the query originates. For example, internal users within a VPC can resolve to private IP addresses using the private hosted zone, while external users on the public internet resolve to public IP addresses using the public hosted zone. This configuration provides flexibility and enhanced security by controlling access to different resources based on the origin of the DNS query.

Route 53 offers us interoperability, meaning we can use it to register or host a domain if we already have one. If we already have a domain registered and want Route 53 to host that domain. In this case, we’ll provide Route 53 with the domain name we have purchased and specify if we want a public-hosted zone for this domain or a private-hosted zone. Route 53 will then create the domain’s zone files and name servers, and we’d need to update the hosted server’s details on the third-party service we used to register the domain.

Health checks in Route 53

AWS Route 53 health checks are a useful and powerful feature. Health checks are independent of resource records and provide separate mechanisms to monitor a resource’s health. Health checks also allow us to monitor the health and availability of endpoints, such as web servers, load balancers, or other endpoints.

The health checks in Route 53 provide us with a lot of flexibility. We can configure custom health checks based on our requirements. Health checks continuously monitor the specified endpoints by sending them HTTP, TCP, or HTTPS requests regularly. Based on the evaluation criteria, endpoints are classified as healthy or unhealthy. If an endpoint is determined to be unhealthy, Route 53 automatically redirects the traffic to healthy endpoints.

Health checks are performed by a fleet of health checkers distributed globally. The health checkers evaluate the health of an endpoint based on the response time and the failure thresholdFailure threshold refers to the number of consecutive request responses.. If we want to check the health of systems hosted on the public internet, we need to allow these checks to occur from health checkers. Route 53 aggregates the data from the health checkers and determines whether the endpoint is healthy. If more than 18% of health checkers report that the endpoint is healthy, it is considered healthy. Otherwise, it is declared unhealthy.

Health check criteria

The health checkers determine the health of an endpoint based on its response time. The response times differ for health check request types:

• HTTP/HTTPS: A successful health check requires the endpoint to send back an HTTP status code in the 2xx or 3xx range within two seconds after the connection is established.

• TCP: To ensure a healthy endpoint, Route 53 expects a TCP connection to be established within 10 seconds.

• HTTP/HTTPS with string matching: Route 53 needs to connect to the endpoint within four seconds, and the endpoint should send back a status code in the 2xx or 3xx range within two seconds after connecting. Route 53 then searches for the specified string, which should be present in the first 5120 bytes of the response body. The health check fails if the string is unavailable in the first 5120 bytes of the response.

Other health checks offered by Route 53 are:

• Calculated health checks: Calculated health checks aggregate results from multiple health checks, providing a nuanced assessment of resource health. A parent health check, which can monitor up to 255 child health checks, is the primary monitor for groups of related resources. This hierarchical structure offers a comprehensive approach to infrastructure health monitoring.

• Health checks using CloudWatch alarms: CloudWatch alarms can be configured to monitor the resources. Route 53 then monitors the data stream associated with a CloudWatch alarm, reflecting the metric the alarm monitors. If the stream indicates an “OK” state, the resource is healthy; if it indicates an “ALARM” state, the resource is unhealthy. When the stream lacks sufficient information, the health check status depends on the configured health check setting.

Roting policies offered by Route 53

Routing policies are the rules and algorithms that route traffic to different endpoints like IP addresses, AWS resources, or other domain names based on various criteria. These routing policies provide flexibility and control over how traffic is distributed to different endpoints, allowing users to optimize the performance, availability, and cost-effectiveness of their applications and services hosted on AWS. Route 53 supports various routing policies to control how DNS queries are answered. These include:

• Simple routing

• Failover routing

• Weighted routing

• Latency-based routing

• Geolocation routing

• Geoproximity routing

• Multi-value routing

• IP-based routing

Each of these routing policies is suitable for different scenarios.

Conclusion

AWS Route 53 is a robust DNS web service offered by Amazon Web Services, operating on an infrastructure as a service model and providing scalable and highly available domain management. It hosts domain registration, hosting, and DNS routing, leveraging top-level domain registries and offering interoperability. With its globally resilient service, Route 53 ensures continuous functionality even during regional outages. Health checks monitor resource health, offering flexibility and customization options. Routing policies optimize traffic flow, catering to various scenarios and controlling traffic distribution. In addition, Route 53 supports advanced features like calculated health checks and routing policies for comprehensive infrastructure management and optimization.