Route 53 Flashcards
What is Route 53?
A highly available, scalable, fully managed DNS
What does a Route 53 record do and what are the 5 things it contains?
It defines how traffic should be routed for a domain and contains
1. Domain/subdomain name
2. Record type (A, AAAA, CNAME, NS)
3. Value (IP address)
4. Routing policy
5. TTL
What does an A record map?
Hostname to IPv4
What does an AAAA record map?
Hostname to IPv6
What does a CNAME record map?
Hostname to another hostname
What does a NS record map?
Name servers for a hosted zone
What are the two types of hosted zones?
- Public - Can be resolved on the internet
- Private - Can only be resolved within one or more VPCs
What does a record TTL do?
Defines a period of time for a client to cache a DNS record before it expires
When would you use an Alias over a CNAME?
Alias’s work for root domains and non root domains whereas CNAME records only work for non root domains. They are also free of charge and have a native health check
Can you set a TTL for Alias records?
No, Alias record TTL’s are set automatically by Route 53
Is it possible to set an Alias record for an EC2 DNS name?
No
List the 8 different routing policy types Route 53 supports.
- Simple
- IP-based
- Weighted
- Failover
- Multi-value answer
- Latency
- Geolocation
- Geoproximity
When should you use a simple route policy?
Typically used to route traffic to a single resource (although multiple values can be return and one will be chosen at random by the client). Cannot be associated with a health check
When should you use a weighted route policy?
When you need to control the % of requests that go to each specific resource. Note, the % does not need to add to 100%. Traffic (%) = [weight of record]/[sum of all record weights]. Note, if all records have a weight of 0, traffic will be distributed evenly.
When should you use a latency route policy?
Directs based on latency between users and AWS regions. Records are associated with a region and the one with the lowest latency for the user will be used.
What are the 3 things a health check can be based on?
- Monitoring a specific endpoint
- Monitoring other health checks
- Monitoring CloudWatch alarms
When should you use failover route policy?
When you want to require a health check to be made to ensure the downstream system is healthy before returning a DNS record
When should you use a geolocation route policy?
When you want to route based on the user location. Be sure to create a default record incase there is no location match
When should you use a geoproximity route policy?
When you require the ability to shift more traffic to resources based on a configurable bias value
When should you use IP-based route policy?
When you know the CIDRs for your clients ahead of time
When should you use multi-value route policy?
When you want to route to multiple different resources and return multiple DNS entries. Related to health checks.
