Basics of Amazon Route 53 [Part -1]

What is Amazon Route 53?

Amazon Route 53 is a highly available and scalable authoritative cloud Domain Name System (DNS) service. It connects the Internet traffic to appropriate servers hosting the requested Web application. In addition, route 53 also facilitates health-checking and domain name registration of services. The design of route 53 aims at providing a highly reliable and cost-effective approach for routing end-users to Internet applications. Why the name Route 53! AWS Route 53 takes its name from the Port 53, which handles DNS for both the TCP and UDP traffic requests, the term Route may signify the routing, or perhaps the popular highway naming convention in the USA.

Before going deep into understanding Amazon Route 53, We should be aware of some useful terminologies :

Internet Protocol (IP) : It is a numerical label assigned to devices and used by computers to identify each other on a network.

Domain Name System (DNS) : They are used to convert human-readable domain names into IP addresses.

Domain Registrars : A authority that can assign domain names. Some popular ones are Domain.com, Bluehost, Network Solutions, HostGator, GoDaddy and Amazon Route 53 itself.

DNS hierarchy

Root server : Root servers are DNS nameservers that operate in the root zone. These servers can directly answer queries for records stored or cached within the root zone, and they can also refer other requests to the appropriate Top Level Domain (TLD) server.

Top Level Domain : The TLD servers are the DNS server group one step below root servers in the DNS hierarchy, and they are an integral part of resolving DNS queries. Ex : .com, .net, .in and .org.

Domain : Domains are your standard URLs like amazon.com and google.com.

Subdomains : Subdomains are a unique URL that lives on your purchased domain as an extension in front of your regular domain like www.google.com and docs.google.com.

Hosted Zone : It’s the way AWS describes the information you provide to define how traffic aimed at your domain name will be managed. A hosted zone is a container for records, and records contain information about how you want to route traffic for a specific domain, such as example.com, and its subdomains (web.example.com, admin.example.com). A hosted zone and the corresponding domain have the same name. When we create a public hosted zone, it automatically creates an SOA and NS that are unique to each hosted zone.

DNS Records : DNS records are what contain the actual information that other browsers or services need to interact with, like your server’s IP address. Nameservers, on the other hand, help store and organize those individual DNS records. Nameservers are the physical phone book itself and DNS records are the individual entries in the phone book.

Start of authority (SOA) : It contains info on hosted zones. Type of resource record that every DNS must begin with, it contains the following information:
1. Contains the owner info(email id).
2. Contains info of authoritative server.
3. Serial number which is incremented with changes to the data zones.(In case of updates).
4. Stores the name of the server supplying the data.
5. Stores the admin zone.
6. Current version of the data file.
7. Time to live.

Name Server (NS) records : As discussed earlier it is a physical phone book itself. Nameservers play an important role in connecting a URL with a server IP address in a much more human-friendly way. Nameservers look like any other domain name. When you look at a website’s nameservers, you’ll typically see a minimum of two nameservers (though you can use more). Here’s an example of what they look like:
ns-380.awsdns-47.com
Ns-1076.awsdns-06.org
They are used by top-level domain servers to direct traffic to the content DNS server. It specifies which DNS server is authoritative for a domain. It is of 4 types recursive resolvers, root nameservers, TLD nameservers, and authoritative nameservers.

Time To Live (TTL) : Length of time the DNS record is cached on the server for in seconds. Default is 48 hours.

Canonical Name (CName) : A CNAME, or Canonical Name record, is a record that points to another domain address rather than an IP address. For example, say you have several subdomains, like www.mydomain.com, mail.mydomain.com etc and you want these subdomains to point to your main domain name mydomain.com.

Alias Record : You will use an ALIAS record when you want the domain itself (not a subdomain) to “point” to a hostname. The ALIAS record is similar to a CNAME record, which is used to point subdomains to a hostname. The CNAME record only can be used for subdomains, so the ALIAS record fills this gap.

How DOES THE AWS Route 53 service work?

1. The domain name is first registered with AWS Route 53 or any Domain registrar, which is then configured to route Internet traffic to the servers hosting the domain name.
2. End-users enter the domain name or the complete URL into the browser search bar.
3. The ISP routes the request to a DNS resolver, a tool that converts the domain name into its IP address.
4. The DNS resolver then forwards the user request to a DNS root name server, which is then directed to its Top Level Domain (TLD) server and ultimately, to AWS Route 53.
5. The Route 53 authoritative name server returns the IP address of the domain name to the DNS resolver.
6. Now that the DNS resolver has the required IP address, it can forward the user request to the appropriate server hosting the content as per the configurations of the AWS Route 53 service.

Amazon Route 53 functions :

1. Dns resolver : A DNS resolver, also called a recursive resolver, is a server designed to receive DNS queries from web browsers and other applications. The resolver receives a hostname — for example, www.example.com — and is responsible for tracking down the IP address for that hostname. AWS Route 53 supports both IPv4 and IPv6 formats.

2. Traffic management : Intelligent traffic routing based on key parameters including proximity, the health of endpoints and latency. Let’s suppose your domain registrar is GoDaddy, then you can direct that traffic to Route 53.

3. Availability management : It checks the health of servers, load balancers, S3 and other resources. Route 53 directs internet traffic to healthy target instances as per the specified configurations. In event of an outage, the health-checking agents will route the traffic to healthy endpoints. The health check feature generates CloudWatch metrics that can further trigger AWS Lambda functions to perform appropriate corrective actions.

4. Domain registration : The facility of domain registration services is the core of Amazon route 53. Users can search for available domain names and register a domain name according to their choice. Furthermore, users also have the option of transferring in existing domain names for management by route 53.

5. Geo DNS and Latency Based Routing: Reduce latency and improve the end-user experience by routing traffic from servers closest to end-users.

6. S3 and CloudFront Zone Apex Support : If you use Amazon CloudFront and S3 for delivering website content, then visitors to your website could access the site at the zone apex. The zone apex is the root domain. For instance, visitors could access the website as xyz.com rather than www.xyz.com. It also creates Custom SSL certificates without requirements for proprietary code or complicated configurations.

7. Private DNS for Amazon VPC: Amazon route 53 documentation presents the private DNS for Amazon VPC as a highly crucial feature in route 53. This feature helps in the management of custom domain names for internal AWS resources. Most important of all, the process does not involve the exposure of DNS data to the public internet.

8. Management Console: A simple and intuitive management console allows users to view resources and perform operational tasks. The management console is also offered as a mobile app. Users can further manage Route 53 controls such as the DNS record modification permission using the AWS Identity and Access Management service.

In part 2 of this series, I will be covering creation of hosted zone, records and DNS routing.

Blog Pundit: Bhupender Singh

Opstree is an End to End DevOps solution provider

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