Stephane Maarek의 「Ultimate AWS Certified Developer Associate 2021 - NEW!」 강의 내용 정리

Route 53

Route 53 is a managed DNS(domain name system)
DNS is a collection of rules and records which helps clients understand how to read a server through its domain name
Route 53 can use:

• public domain names you own/buy
• private domain names that can be resolved by your instances in your VPCs

Route 53 has advanced features such as:

• load balancing
• health checks
• routing policy

$0.5 per month per hosted zone

DNS Records TTL(time to live)

→ not to overload DNS
High TTL: less traffic on DNS / possibly outdated records
Low TTL: more traffic on DNS / records are outdated for less time / easy to change records
TTL is mandatory for each DNS record

CNAME vs Alias

AWS resources expose an AWS hostname
→ CNAME: points a hostname to any other hostname / only for non root domain
→ Alias: points a hostname to an AWS resource / works for both root and non root domain / free of charge / native health check

Routing Policy

Simple Routing Policy

Use when you need to redirect to a single resource
You can’t attach health checks to simple routing policy
If multiple values are returned, a random one is chosen by the client

Weighted Routing Policy

Control the % of the requests that go to specific endpoint
Helpful to test 1% of traffic on new app version for example
Helpful to split traffic btw two regions
Can be associated w/ health check

Latency Routing Policy(most useful)

Latency will evaluate the latency results and help your users get a DNS response that will minimize their latency (e.g. response time)
Redirect to the server that has the least latency close to us
Super helpful when latency of users is a priority
Latency is evaluated in terms of user to designated AWS region

Failover Routing Policy

Health Checks

• Have n(default: 3) health checks failed → unhealthy
• Have n(default: 3) health checks passed → healthy
• Default health check internal: 30s
• About 15 health checkers will check the endpoint health
• Health checks can be linked to Route DNS queries

Primary & secondary(for disaster recovery) In case health check of primary resource fails, automatically send back request to secondary one

Geo Location Routing Policy

→ != latency routing policy
This is routing based on user location
zb. Traffic from UK should go to this specific IP!
Should create a default policy, in case there’s no match on location

Multi Value Routing Policy

Use when routing traffic to multiple resources
Want to associate a route 53 health checks with records
Up to 8 healthy records are returned for each Multi Value query
Multi value is not a substitute for having an ELB