Route 53 Concepts

What Is Amazon Route 53?

You can use Amazon Route 53 to help you get a website or web application up and running. Route 53 performs three main functions:

• Register domain names – Your website needs a name, such as example.com. Route 53 lets you register a name for your website or web application, known as a domain name. 
• Route internet traffic to the resources for your domain – When a user opens a web browser and enters your domain name in the address bar, Route 53 helps the Domain Name System (DNS) connect the browser with your website or web application. 
• Check the health of your resources – Route 53 sends automated requests over the internet to a resource, such as a web server, to verify that it's reachable, available, and functional. You also can choose to receive notifications when a resource becomes unavailable and choose to route internet traffic away from unhealthy resources.

Amazon Route 53 is a highly available and scalable cloud Domain Name System (DNS) web service.

 It is designed to give developers and businesses an extremely reliable and cost-effective way to route end users to Internet applications by translating names like www.example.com into the numeric IP addresses like 192.0.2.1 that computers use to connect to each other.

Amazon Route 53 effectively connects user requests to infrastructure running in AWS – such as Amazon EC2 instances, Elastic Load Balancing load balancers, or Amazon S3 buckets – and can also be used to route users to infrastructure outside of AWS. 

How Domain Registration Works

If you want to create a website or a web application, you start by registering the name of your website, known as a domain name. Your domain name is the name, such as example.com, that your users enter in a browser to display your website.

Now you can register your service instances using Amazon Route 53 Auto Naming APIs and specify settings for A, AAAA, CNAME, and SRV records, and for Route 53 alias records that route traffic to an ELB load balancer.

Supported DNS Resource Record Types

• A (Address) Format
  • is an IPv4 address in dotted decimal notation for e.g. 192.0.2.1
• AAAA Format
  • is an IPv6 address in a colon-separated hexadecimal format
• CNAME Format
• is the same format as a domain name
• A canonical name record type that is used to specify that a domain name is the alias of another domain, the "canonical" domain.
• CNAME Rules:
• DNS protocol does not allow creation of a CNAME record for the top node of a DNS namespace, also known as the zone apex for e.g. the DNS name example.com registration, the zone apex is example.com, a CNAME record for example.com cannot be created, but CNAME records can be created for www.example.com, newproduct.example.com etc.
• 
  
• If a CNAME record is created for a subdomain, any other resource record sets for that subdomain cannot be created for e.g. if a CNAME created for www.example.com, not other resource record sets for which the value of the Name field is www.example.com can be created
• 
  
• MX (Mail Xchange) Format
  • contains a decimal number that represents the priority of the MX record, and the domain name of an email server
• NS (Name Server) Format
  • An NS record identifies the name servers for the hosted zone. The value for an NS record is the domain name of a name server.
• PTR Format
  • A PTR record Value element is the same format as a domain name.
• SOA (Start of Authority) Format
  • SOA record provides information about a domain and the corresponding Amazon Route 53 hosted zone
• SPF (Sender Policy Framework) Format
  • SPF records were formerly used to verify the identity of the sender of email messages, however, is not recommended
  • Instead of an SPF record, a TXT record that contains the applicable value is recommended
• SRV Format
  • An SRV record Value element consists of four space-separated values.The first three values are decimal numbers representing priority, weight, and port. The fourth value is a domain name for e.g. 10 5 80 hostname.example.com
• TXT (Text) Format
• A TXT record contains a space-separated list of double-quoted strings. A single string includes a maximum of 255 characters. In addition to the characters that are permitted unescaped in domain names, space
  is allowed in TXT strings
• A brief summary:

Alias resource record sets

• Route 53 supports alias resource record sets, which enables routing of queries to a CloudFront distribution, Elastic Beanstalk, ELB, an S3 bucket configured as a static website, or another Route 53 resource record set
• Alias records are not standard for DNS RFC and are a Route 53 extension to DNS functionality
• Alias records help map the apex zone (root domain without the www) records to the load balancer DNS name as the DNS specification requires “zone apex” to point to an ‘A’ record (ip address) and not to a CNAME
• Route 53 automatically recognizes changes in the resource record sets that the alias resource record set refers to for e.g. for a site pointing to a load balancer, if the ip of the load balancer changes, Route 53 will reflect those changes automatically in the DNS answers without any changes to the hosted zone that contains resource record sets
• If an alias resource record set points to a CloudFront distribution, a load balancer, or an S3 bucket, the time to live (TTL) can’t be set; Route 53 uses the CloudFront, load balancer, or Amazon S3 TTLs.