Amazon Route 53

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

What is DNS?

DNS is a service that translates human readable domain names (e.g., www.example.com) to an IP address (e.g., 192.0.2.44)

It does so by communicating with a set of Name Servers (that have their own set of database of mappings) who guide to the right Name Server that actually contains that domain name mapping.
Following diagram shows a typical process of resolving domain name to an IP address

DNS Query Sequence

Image courtesy of AWS

Resolver enables recursive DNS for your VPC or on-premise networks
Traffic Flow allows you to configure how should the traffic (targeted for your application) be routed to your application
Private DNS for VPC enables custom domain names for internal (to AWS) resources without exposing DNS data to the internet.
Health Checks and Monitoring can be done by Route 53 for your application servers.
Domain Registration can be done through Route 53

Key Points

Route 53 is highly available, and its designed & implemented in a (globally) widely distributed manner.
Route 53 integrates well with ELB to allow load balancing and scaling.

Route 53 supports following Routing Policies

Simple – simply routes the traffic to specific AWS resource
Failover – allows Primary and Secondary target to route traffic (this is also known as Active-Passive Failover)
Geolocation – routes all traffic from a defined geography area to specific AWS resource
- Geographic locations are defined at the level of Continent, Country, or at State (in case of USA).
Geo-proximity – enables routing of traffic based on end-user’s location against the nearest (in context) AWS resource location
- You can adjust the proximity range of your AWS resources by using a parameter called “bias”
- A “bias” can shrink proximity range based on negative value, or expand based on positive bias value
Latency – enables access to your AWS resource based on latency (between end user and target resource)
Multi-value Answer – allows return of multiple AWS resources (for a specific DNS query)
- Route 53 only returns the values of healthy resources
Weighted – allows you to distribute traffic to different AWS resources in proportion to weights assigned to them

Amazon Route 53 currently supports the following DNS record types:

A (address record)
AAAA (IPv6 address record)
CNAME (canonical name record)
CAA (certification authority authorization)
MX (mail exchange record)
NAPTR (name authority pointer record)
NS (name server record)
PTR (pointer record)
SOA (start of authority record)
SPF (sender policy framework)
SRV (service locator)
TXT (text record)
Amazon Route 53 also offers alias records, which are an Amazon Route 53-specific extension to DNS.
Alias Records allow routing traffic to AWS resources, such as ELB, CloudFront, Elastic Beanstalk , API Gateways, VPC Interface Endpoints, and Amazon S3 buckets (configured as websites).
Alias record typically have a type of A or AAAA, but they work like a CNAME record. Using an alias record, you can map your record name (example.com) to the DNS name for an AWS resource(elb1234.elb.amazonaws.com). Resolvers see the A or AAAA record and the IP address of the AWS resource.

Route 53 is billed for following components:

Hosted Zones – per each Hosted Zone
DNS Queries – per 1 Billion queries per month
- Charges vary by Query type: Standard Queries, Latency Based Routing Queries, Geo DNS and Geo-proximity Queries
- Charges are tiered – different rate for first 1 Billion queries per month, and for over first Billion queries (each month)
- Alias -based Queries are not charged
Traffic Flow – per Policy Record per month
Health Checks – per Health Check per month
- varies by Health Check type
- varies by Health Checks on AWS Endpoints vs Non-AWS Endpoints
Route 53 Resolver – per Elastic Network Interface (ENI) hour, and per Billion queries served per month
Doman Name Registration / Transfers – per Domain Name