Route 53 Flashcards
What is it called Route53?
TCP/UDP Port 53 is DNS
What is Route53?
Amazon’s DNS service which extends the functionality of DNS
What is the difference between Alias and CNAME records?
Alias are AWS’s own implementation which will automatically update the value based on any changes to the target resource. You can use an alias record as the root/apex record
CNAMEs are used to give another record an alias. With regular DNS CNAMEs cannot be used at the root level domain. (CNAME Flattening)
Do ELBs have IPs?
ELBs only have a DNS name
What is Simple Routing Policy?
Simple routing policy is the default policy for record sets and are the standard way of routing similar to a regular DNS server. There is no extra behaviorial changes.
Client request -> Route53 -> Resource
What is Weighted Routing Policy?
Used to route traffic using weights that you set on each weighted record set to a given resource.
20% of client requests -> resource1
80% of client requests -> resource2
What is Latency Routing Policy?
Used to route traffic to the record set resource with the lowest latency.
What is Failover Routing Policy?
Used to set an Active/Passive set of records. Uses health check to determine when to failover.
Client request -> Route53 -> Primary Resource (If health check passes)
Client request -> Route53 -> Secondary Resource (If health check fails)
What is Geolocation Routing Policy?
Used to route all traffic from a specific location to a target resource.
Client request (from US) -> Route53 -> US Servers/resources Client request (from EU) -> Route53 -> EU Servers/resources
What is Multivalue Routing Policy?
Used to route traffic randomly to a list of resources, these resources are maintained via health checks, if health check fails the resource is removed from the list until it passes health check.
Client request -> Route 53 -> (randomResourceThatPassesHealthcheck)
What is Geoproximity Routing Policy (Traffic Flow)?
Used to route traffic based on physical distance between a query and your resource. You can route more or less traffic to each resource by specifying a bias (-1 to-99, 1 to 99, positve is more, negative is less)
Given EC2 instances:
1 on US-west1
1 on US-east1
Client request from LA -> Route53 -> resource-on-us-west1
What is a start of authority record (SoA)?
Record with information about a given DNS zone
Contains information about:
- the authoritative server
- administrator
- current version of zone file
- TTL
- Amount of time a secondary name server can use data before it must be refreshed or expire
Given a choice between Alias and CNAME records which to choose?
Choose Alias
Why is an Alias record better than a CNAME record?
Alias records automatically update their values based on any changes to their AWS resource
They can also use cname flattening AKA use a record other than IPv4/A as the root domain
Is there a limit to the number of domain names you can have on Route53?
There is a soft-limit of 50. However you can increase that amount by calling AWS support
