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Note
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Route 53 is a highly available, scalable, fully managed and Authoritative DNS
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Route 53 is also a Domain Register
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Can set Records: here
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CNAME vs Alias: here
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3 types of Health Checks: here
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7 types of Routing Policies: here
Amazon Route 53
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A highly available, scalable, fully managed and Authoritative DNS
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Authoritative means the customer can update the DNS records
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Route 53 is also a Domain Register
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Ability to check the health of your resources
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The only AWS service which provides 100% availability SLA
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Route 53 is a reference to the traditional DNS port
Records
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How you want to route traffic for a domain
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Each record contains:
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Domain/subdomain Name — e.g., example.com
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Record Type — e.g., A or AAAA
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Value — e.g., 12.34.56.78
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Routing Policy — how Route 53 responds to queries
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TTL - amount of time the record cached at DNS Resolvers
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Route 53 supports the following DNS record types:
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(must know) A / AAAA / CNAME / NS
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(advanced) CAA / DS / MX / NAPTR / PTR / SOA / TXT / SPF / SRV
Record Types
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A - maps a hostname to IPv4
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AAAA - maps a hostname to IPv6
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CNAME - maps a hostname to another hostname
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The target is a domain name which must have an A or AAAA record
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Can’t create a CNAME record for the top node of a DNS namespace (Zone Apex)
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NS - Name Servers for the Hosted Zone
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Control how traffic is routed for a domain
Hosted Zones
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A container for records that define how to route traffic to a domain and its subdomains
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Public Hosted Zones - contains records that specify how to route traffic on the Internet (public domain names)
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Private Hosted Zones - contain records that specify how you route traffic within one or more VPCs (private domain names)
Records TTL (Time To Live)
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High TTL - e.g. 24 hr
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Less traffic on Route 53
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Possibly outdated records
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Low TTL - e.g. 60 sec.
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More traffic on Route 53 ($$)
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Records are outdated for less time
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Easy to change records
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Except for Alias records, TTL is mandatory for each DNS record
CNAME vs Alias
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AWS Resources (load Balancer, CloudFront…) expose an AWS hostname:
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CNAME:
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Points a hostname to any other hostname (app.mydomain.com ⇒ blabla.anything.com)
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ONLY FOR NON ROOT DOMAIN (aka. something.mydomain.com)
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Alias:
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Points a hostname to an AWS Resource (app.mydomain.com ⇒ blabla.amazonaws.com)
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Works for ROOT DOMAIN and NON ROOT DOMAIN (aka. mydomain.com)
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Free of charge
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Native health check
Alias Records
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Maps a hostname to an AWS resource
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An extension to DNS functionality
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Automatically recognizes changes in the resource’s IP addresses
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Unlike CNAME, it can be used for the top node of a DNS namespace (Zone Apex), e.g. example.com
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Alias Record is always of type A/AAAA for AWS resources (IPv4 / IPv6)
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You can’t set the TTL
Alias Records Targets
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Elastic Load Balancers
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CloudFront Distributions
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API Gateway
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Elastic Beanstalk environments
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S3 Websites
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VPC Interface Endpoints
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Global Accelerator accelerator
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Route 53 record in the same hosted zone
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You cannot set an ALIAS record for an EC2 DNS name
Health Checks
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HTTP Health Checks are only for public resource
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Health Check ⇒ Automated DNS Failover:
1.
Health checks that monitor an endpoint (application, server, other AWS resource)
2.
Health checks that monitor other health checks (Calculated Health Checks)
3.
Health checks that monitor CloudWatch Alarms
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Health Checks are integrated with CW metrics
Monitor an Endpoint
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About 15 global health checkers will check the endpoint health
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Health Checks pass only when the endpoint responds with the 2xx and 3xx status codes
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Health Checks can be setup to pass / fail based on the text in the first 5120 bytes of the response
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Configure you router/firewall to allow incoming requests from Route 53 Health Checkers
Calculated Health Checks
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Combine the results of multiple Health Checks into a single Health Check
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You can use OR, AND, or NOT
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Can monitor up to 256 Child Health Checks
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Specify how many of the health checks need to pass to make the parent pass
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Usage: perform maintenance to your website without causing all health checks to fail
Private Hosted Zones
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Route 53 health checkers are outside the VPC
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They can’t access private endpoints
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You can create a CloudWatch Metric and associate a CloudWatch Alarm, then create a Health Check that checks the alarm itself
Routing Policies
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Define how Route 53 responds to DNS queries
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Don’t get confused by the word “Routing”
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It’s not the same as Load balancer routing which routes the traffic
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DNS does not route any traffic, it only responds to the DNS queries
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Route 53 Supports the following Routing Policies
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Simple
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Weighted
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Failover
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Latency based
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Geolocation
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Multi-Value Answer
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Geoproximity (using Route 53 Traffic Flow feature)
Simple Routing Policies
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Typically, route traffic to a single resource
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Can specify multiple values in the same record
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If multiple values are returned, a random one is chosen by the client
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When Alias enabled, specify only one AWS resources
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Can’t be associated with Health Checks
Weighted Routing Policies
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Control the % of the requests that go to each specific resource
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Assign each record a relative weight:
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DNS records must have the same name and type
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Can be associated with Health Checks
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Use cases: load balancing between regions, testing new application versions …
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Assign a weight of 0 to a record to stop sending traffic to a resource
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If all records have weight of 0, then all records will be returned equally
Latency-based Routing Policies
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Redirect to the resource that has the least latency close to us
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Super helpful when latency for users is a priority
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Latency is based on traffic between users and AWS Regions
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Germany users may be directed to the US
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Can be associated with Health Checks
Failover (Active-Passive) Routing Policies
Geolocation Routing Policies
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Different from Latency-based
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This routing is based on user location
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Specify location by Continent, Country or by US State
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Should create a “Default” record
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Use cases: website localization, restrict content distribution, load balancing
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Can be associated with Health Checks
Geoproximity Routing Policies
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Route traffic to your resources based on the geographic location of users and resources
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Ability to shift more traffic to resources based on the defined bias
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To change the size of the geographic region, specify bias values:
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To expand (1 to 99) - more traffic to the resource
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To shrink (-1 to -99) - less traffic to the resource
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Resource can be:
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AWS resources (specify AWS region)
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Non-AWS resources (specify Latitude and Longitude)
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You must use Route 53 Traffic Flow to use this feature
IP-based Routing Policies
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Routing is based on clients’ IP addresses
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You provide a list of CIDRs for your clients and the corresponding endpoints/locations
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Use cases: Optimize performance reduce network costs
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Example: route end users from a particular ISP to a specific endpoint
Multi-Value Routing Policies
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Use when routing traffic to multiple resources
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Route 53 return multiple values/resources
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Can be associated with Health Checks (return only values for healthy resources)
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Up to 8 healthy records are returned for each Multi-Value query
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Multi-Value is not a substitute for having an ELB
Traffic flow
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Simplify the process of creating and maintaining records in large and complex configurations
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Visual editor to manage complex routing decision trees
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Configurations can be saved as Traffic Flow Policy
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Can be applied to different Route 53 Hosted Zones
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Supports versioning
Domain Registar vs DNS Service
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You buy or register your domain name with a Domain Registrar typically by paying annual charges (e.g., GoDaddy, Amazon Registrar Inc., …)
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The Domain Registrar usually provides you with a DNS service to manage your DNS records
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But you can use another DNS service to manage your DNS records
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Example: purchase the domain from GoDaddy and use Route 53 to manage your DNS records
3rd Party Registrar with Amazon Route 53
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If you buy your domain on a 3rd party registrar, you can still use Route 53 as the DNS Service provider
1.
Create a Hosted Zone in Route 53
2.
Update NS Records on 3rd party website to use Route 53 Name Servers
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Domain Registrar ≠ DNS Service
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But every Domain Registrar usually comes with some DNS features
