Route 53 Flashcards
Describe Route 53
Route 53 is a high available, scalable, full managed and Authoritative DNS
Authoritative DNS means that you (the customer) can update the DNS records
It is also a Domain Registrar
Name 4 record types and what they do
A - maps a hostname to IPv4
AAAA - MAPS HOSTNAME TO ipV6
CNAME - maps hostname to another hostname
NS - name servers for the hosted zone
TTL stands for?
Time to Live
True or False
You can set an ALIAS record for an EC2 DNS name.
False! You CAN NOT set an ALIAS record for an EC2 DNS name.
Examples of ALIAS targets are:
- elastic load balancers
- amazon cloudfront
- s3 websites
- amazon API gateway
What’s the main difference between CNAME records and ALIAS records?
Alias records can be set for the root domain, eg. example.com
… whereas CNAME records can only be set for subdomains, eg. api.example.com
Describe Route 53 routing policies
Routing policies define how Route 53 responds to DNS queries
The routing policies are:
- simple
- weighted
- failover
- latency based
- geolocation
- multi-value answer
- geoproximity
Describe weighted routing policy
weighted policy lets you control the percentage of the request that go to each specific resource
eg.
ip 1.2.3.4 gets 70%
ip 4.5.6.7 gets 30%
assigning weight of 0 stops sending traffic to the resource
describe the latency based routing policy
redirect to the resource that has the least latency to us
great for applications where low latency is a priority
Describe a failover routing policy
Failover routing policy lets you declare a secondary record to use if the primary record’s health check fails
describe geolocation routing policy
routing is based on user location - this is different from latency!
specify by continent, country, state, etc
great use cases: website localization, restrict content distribution, load balancing
describe geoproximity routing policy
routes traffic to resources based on the geographic location of users and resources
shift more or less traffic to resources based on a defined bias
resources are specified by either AWS region, or latitude and longitude
use case: when you need to shift traffic from one resource to another
describe route 53 traffic flow
traffic flow is a visual editor that helps manage complex routing decision trees
these can be saved as traffic flow policies
- supports versioning
describe multi-value routing policy
let’s you route traffic to multiple resources (can be based on health checks)
up to 8 healthy records are returned for each multi-value query
think of this as a client-side load balancer
You have purchased mycoolcompany.com on Amazon Route 53 Registrar and would like the domain to point to your Elastic Load Balancer my-elb-1234567890.us-west-2.elb.amazonaws.com.
Which Route 53 Record type must you use here?
ALIAS.
CNAME does not support root level domains
You have deployed a new Elastic Beanstalk environment and would like to direct 5% of your production traffic to this new environment. This allows you to monitor for CloudWatch metrics and ensuring that there’re no bugs exist with your new environment.
Which Route 53 Record type allows you to do so?
Weighted
Weighted Routing Policy allows you to redirect part of the traffic based on weight (e.g., percentage). It’s a common use case to send part of traffic to a new version of your application.
You have updated a Route 53 Record’s myapp.mydomain.com value to point to a new Elastic Load Balancer, but it looks like users are still redirected to the old ELB.
What is a possible cause for this behavior?
Because of the TTL.
Each DNS record has a TTL (Time To Live) which orders clients for how long to cache these values and not overload the DNS Resolver with DNS requests. The TTL value should be set to strike a balance between how long the value should be cached vs. how many requests should go to the DNS Resolver.
You have an application that’s hosted in two different AWS Regions us-west-1 and eu-west-2. You want your users to get the best possible user experience by minimizing the response time from application servers to your users.
Which Route 53 Routing Policy should you choose?
Latency.
Latency Routing Policy will evaluate the latency between your users and AWS Regions, and help them get a DNS response that will minimize their latency (e.g. response time)
You have a legal requirement that people in any country but France should NOT be able to access your website.
Which Route 53 Routing Policy helps you in achieving this?
Geolocation
You have purchased a domain on GoDaddy and would like to use Route 53 as the DNS Service Provider.
What should you do to make this work?
Create a public hosted zone and update the 3rd party registrar NS records
Public Hosted Zones are meant to be used for people requesting your website through the Internet. Finally, NS records must be updated on the 3rd party Registrar.
Which of the following are NOT valid Route 53 Health Checks?
a. health check that monitors SQS queue
b. health check that monitors an endpoint
c. health check that monitors other health checks
d. health check that monitors cloudwatch alarms
a. health check that monitors SQS queue
