We live in an age where the internet and digital data drive modern day markets, which results in huge amounts of data being generated and consumed. Hence, it has become very important for online platforms to manage this traffic and serve their customers more efficiently. In this blog we will explore the Amazon Route 53 service and see how it addresses domain name system routing and health check problems.
This blog focuses on the following:
- What is a Domain Name System (DNS)?
- What is Amazon Route 53 and its Benefits?
- Route 53 Health Checks
- How does Route 53 Determine the Status of Health Checks?
- Setting Up Route 53 Health Checks
What is a Domain Name System (DNS)?
Humans often use names, addresses, or some form of identification to identify other humans, objects, and places. For example, if you wish to visit a restaurant, you would need to know the name of the restaurant and the corresponding address that can be used to find the place you wish to visit. Similarly, if you wish to visit a person, you would ask for the person’s address where that individual lives.
The Internet uses domain names to label resources that lie on the internet. You can think of the domain name system as an address book over the internet, used by humans to access resources online.
Every device that is connected to the Internet has a unique address associated with it called the IP address. It can be used by other machines to find the device. An IP address looks something like this, 192.168. 1.1. Hence, remembering these IP addresses can be a tedious task. Therefore, we use domain names (an easy-to-remember address or a name) that humans can keep track of, like google.com, cricbuzz.com, etc. These domain names will have IP addresses associated with them, and the DNS servers will link these domain names to the respective IP addresses, thus eliminating the need for humans to memorize IP addresses.
How do DNS Servers Work?
Suppose a user wishes to visit a website xyz.com and types the domain name in the browser. The request goes to the DNS server that translates or resolves the domain name (xyz.com) to a machine-readable IP address and, in response, returns the IP address that is associated with the domain name. The client then sends the resolved IP address to the web server and, in return, receives the content the user requested.
What is Amazon Route 53 and its Benefits?
Amazon Route 53 is a highly available and scalable Domain Name System (DNS) service. It is used to perform the following functions:
- Domain registration: This service can be used to register domain names for websites. It selects the domain names and registers them using the AWS console.
- DNS routing: It helps connect a browser to a website or web server when a user enters the domain name. It routes traffic to the end user, ensuring the best experience.
- Health Check: It monitors the health and performance of the resources. It does that by sending automated requests over the internet to a resource.
- Weighted round-robin load balancing: It spreads traffic between several services by using a round-robin algorithm.
Benefits of Route 53
- Highly Scalable and Reliable: It can handle large numbers of queries (millions) without the need for human interaction and offers a consistent ability to route users to applications.
- Ease of use: It is very easy to configure DNS settings and the service provides a fast response to queries.
- Secure: The user secures the access rights by integrating Route 53 with AWS IAM, which offers numerous security features.
Route 53 Health Checks
These checks are used to monitor the health and performance of your web applications, web servers, and other resources. These health checks monitor the following:
- The health of a resource you specify.
- The status of other health checks.
- The status of an Amazon CloudWatch alarm.
Here is an overview of how the health checks work.
- You create a health check and specify values that define how you want the health check to work, following values need to be specified:
- The IP address or domain name of the endpoint that Route 53 should monitor.
- The protocol that Amazon Route 53 will use for the check.
- Frequency of Route 53 to send a request to the endpoint.
- Failure threshold before Route 53 considers it unhealthy.
- Route 53 sends requests to the endpoint at the specified interval.
- If there is a response from the endpoint, Route 53 considers the endpoint to be healthy with no action.
- If there is no response to the request, Route 53 counts the number of consecutive requests not responded
by the endpoint,
- If the count reaches the failure threshold value, the endpoint is considered unhealthy.
- If the endpoint responds before the failure threshold value is met, Route 53 resets the count to 0.
- You can configure CloudWatch and Simple Notification Service to trigger alerts when health checks return unhealthy results. You can also check the status of your Route 53 health checks in the Route 53 console. For more information, see Monitoring health check status and getting notifications.
How does Route 53 Determine the Status of Health Checks?
There are three types of Amazon Route 53 health checks. Those are:
- Health checks that monitor an endpoint.
- Health checks that monitor other health checks.
- Health checks that monitor CloudWatch alarms.
Let us explore how these health checks work.
Health checks that monitor an endpoint
When a health check is created to monitor an endpoint, the health checkers send requests to the endpoint specified to determine whether the endpoint is healthy. You can specify a location you want Route 53 to use, and also the interval between checks. The health checker evaluates the health of the endpoint based on:
- Response time.
- Whether the endpoint responds to the number of consecutive health checks specified (the failure threshold).
This data from the health checkers is aggregated to determine whether the endpoint is healthy.
Health checks that monitor other health checks
You can also monitor the status of other health checks. This process is called a calculated health check. The parent health checker monitors other health checks called child health checks. Here's how the monitoring works:
- Route 53 adds up the number of healthy child health checks.
- It compares the summed up number to the specified value, if it meets the number the health check gives a positive result.
Health checks that monitor CloudWatch alarms
If your health check is based on a CloudWatch alarm, Route 53 monitors the data stream for the corresponding alarm instead of monitoring the alarm state. If the data stream indicates that the state of the alarm is OK, the health check is considered healthy. If the data stream indicates that the state is alarming, the health check is considered unhealthy. In the event that the data stream doesn't provide enough information to determine the state of the alarm, the health check status depends on the parameters you have set: healthy, unhealthy, or last known status.
Setting Up Route 53 Health Checks
Here is a step-by-step guide to help you set up your first Amazon Route 53 health check,
Step1: Go to AWS Web Console and open Route 53 Service.
Step2: Click on Create health checks.
Step3: Fill in your website and IP details as shown in the image below and then click on Next.
Step4: Set up the CloudWatch alarm. Enter a relevant topic name and the list of email addresses that you wish to notify. Click on Create health check.
There you go! Your Route 53 health check is created, and it will display the status of the associated resource.
Amazon Route 53 is a highly versatile service with various routing, health check, and monitoring capabilities to go along with the DNS solutions it offers. It readily integrates with an exhaustive set of AWS and other cloud services giving it an edge over its competition.
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