Route 53 Flashcards
DNS
Domain Name System which translates the human friendly hostnmaes into the machine IP addresses
www.google.com=>172.217.18.36
DNS is the backbone of the internet
Domain Registrar
Amazon Route 53, GoDaddy,NS
DNS Records
A, AAAA, CNAME, NS
Zone File
contains DNS recors
Name Server
resolves DNS queries (authoritative or non-authoritative)
Top Level Domain (TLD)
.com, .us, .gov, .org
Second Level Domain (SLD
amazon.com, google.com
Route 53
Highly available, scalable, fully managed and authoritative DNS
Authoritative = the customer (you) can update the DNS records
Domain Registrar as well
The only AWS service which provides 100% availability SLA
Route 53 records
how you want to route traffic for a domain
Each record contains:
1. Domain/Subdomain Name- e.g example.com
2. Record Type- e.g. A or AAAA
3. Value- e.g 12.34.56.78
4.Routing Policy- how Route 53 responds to queries
5. TTL- amount of time the record cached at DNS Resolvers.
DNS Record Types that Route 53 SUpports
A/ AAAA/ CNAME/ NS
A
maps a hostname to Ipv4 address
AAAA
maps a hostname to IPv6 address
CNAME
maps a hostname to another hostname
The target is a domain name which must have an A or AAAA record.
NS
Name Servers for the Hosted Zone. They are the DNS names or IP addresses of the servers that can respond to the DNS queries for your hosted Zone.
Hosted Zones
A container for records that define how to route traffic to a domain and its subdomains.
Public Hosted Zones
contains records that specify how to route traffic on the internet (public domain names)
$0.50/month per hosted zone.
Private Hosted ZOnes
contain records that specify how you route traffic with one or more VPCs (private domain names)
URLs you can only access within your private corporate network.
TTL
Time To Live
TTL is saying client please cache this result for duration of the TTL.
purpose is we don’t want to query the DNS too often because we don’t expect records to change a lot, using response we have the client can access the web server and do http request and responses.
CNAME
Points a hostname to any other hostname (app.mydomain.com =>blabla.anything.com)
only for non root domain (aka something.mydomain.com
Alias
Points a hostname to an AWS resource (app.mydomain.com => blabla.amazonaws.com)
works for root domain and non root domain (aka my domain.com)
free of charge and have native health check
Always typeA/AAAA
Alias Record Targets
ELBs
CloudFront Distributions
API Gateway
Elastic Beanstalk environments
S3 websites
VPC Interface Endpoints
Global Accelerator accelerator
Route 53 record in the same hosted zone
you cannot set an alias record for an EC2 DNS name
Routing Policy
Define how Route 53 responds to DNS queries
DNS does not route any traffic, it only responds to the DNS queries.
Simple Routing Policies
Typically, route traffic to a single resource
Can’t be associated with Health Checks
Weighted Routing Policies
control the % of the requests that go to each specific resource
Assign each record a relative weight.
DNS record must have same name and type.
use case: load balancing between regions, testing new application versions.
Assign a weight of 0 to a record to stop sending traffic to a resource.
If all records have a weight of 0, then all records will be returned equally.
Routing Policy Latency Based
Redirect to the resource that has the least latency close to us
latency is based on traffic between users and AWS regions
