Route 53 Flashcards
What are the different record types
A
AAAA
CNAME
NS
What does an A record type map to
A record type maps a hostname to IPv4
What does an CNAME record type map to
CNAME record type maps a hostname to another hostname
The target is a domain name which must have an A or AAAA record
Can’t create for example.com, but you can create for www.example.com
Ex app.mydomain.com => blabla.anything.com
But only for non root domain..(aka “something.mydomain.com”)
This is different from an Alias which points a hostname to an AWS resource
Ex app.mydomain.com => blabla.amazonaws.com
Works for root domain and non root domain (aka “mydomain.com”
Its free of charge and has a native health check
What does an AAAA record type map to
AAAA record type maps a hostname to IPv6
What does an NS record type map to
It is name servers for the hosted zone. It controls how traffic is routed for a domain
What are targets for Alias records
ELBs
CloudFront Distributions
API Gateway
Elastic Beanstalk Env
S3 Websites
Route 53 record in the same hosted zone
You cannot set an ALIAS record for an EC2 DNS name
What are the possible Route 53 records TTL
High TTL - ex 24hr: Less traffic on Route 53, possibly outdated records
Low TTL - ex 60sec: More traffic on Route 53, less outdated records
Except for Alias records, TTL is mandatory for each DNS
Route 53 has multiple routing policies, explain the simple routing policy
It routes traffic to a single resource
Ex Client tries to connect to foo.example.com
Route 53 returns 11.22.33.44
It can specify multiple values in the same record, but a random one is chosen by the client
Ex Client tries to connect to foo.example.com
Route 53 returns 11.22.33.44, 55.66.77.88, 99.11.22.33
Route 53 has multiple routing policies, explain the Weighted routing policy
With weighted you can control the percent of the requests that go to each specific resource. Example, you can have 70% of traffic go to one server, and 30% go to another server. Usually these can be used when load balancing between regions or testing new application versions. It can be associated with health checks
Route 53 has multiple routing policies, explain the Latency-based routing policy
Redirect to the resource that has the least latency close to us. It can be associated with health checks and has a failover capability
Route 53 has multiple routing policies, explain the Failover (active passive) routing policy
DNS requests will be routed to a primary instance with a health check which is mandatory. If the HC fails, the requests will failover to a secondary instance which is passive until the failed HC
Route 53 has multiple routing policies, explain the Geolocation routing policy
This is based on user location. You can specify by country, continent or US state. You should create a default record in case there is no match on location. It can be associated with health checks
Route 53 has multiple routing policies, explain the Geoproximity routing policy
Route traffic based on the geographic location of users and resources. You can change the size of the geographic region by specifying bias values: to expand (1 to 99), to shrink (-1 to -99).
You must use Route 53 traffic flow to use this feature
What is traffic flow in route 53
It allows you to create geoproximity rules which can be saved as traffic flow policy
Route 53 has multiple routing policies, explain the Multi-value routing policy
Use when routing traffic to multiple resources
Route 53 can return multiple values and it can be associated with health checks. Only healthy resources will return values
Up to 8 healthy records are returned for each multi-value query
Route 53 has multiple routing policies, explain the IP Based routing policy
Routing is based on clients IP address. You can route end users from a particular IP to a specific endpoint. You can define CIDR blocks and route IPs under them to specific resources
What are route 53 hosted zones
It is a container for records that define how to route traffic to a domain and subdomains
What are the two types of hosted zones
Public Hosted Zones - contains records that specify how to route traffic on the internet
Private Hosted Zones - contains records that specify how to route traffic with one or more VPCs. Note: you must enable the VPC settings enableDnsHostnames and enableDnsSupport
What is DNSSEC
DNS Security Extensions is a protocol for securing DNS traffic, it verifies DNS data integrity and origin. It protects against Man in the Middle attacks and only works with public hosted zones
How are health checks used in Route 53
HTTP health checks are for public resources
You have health checks that monitor an endpoint (application or server)
Health checks that monitor other health checks (Calculated HC)
Health checks that monitor CW alarms
What is a calculated health check
It is combining multiple health checks into one. You have a parent HC which can monitor up to 256 child HCs. You can specify how many of the HCs need to pass to make the parent HC pass.
What is the HC that monitors an endpoint
You have health checks that monitor an endpoint (application or server)
HC pass only when the endpoint responds with the 2xx and 3xx status codes
HC can be setup to pass/fail based on the text in the first 5120 bytes of the response
How do we have health checks in private hosted zones
By creating a health check outside of the VPC to monitor a cloudwatch alarm within the VPC
How can we have an on premise server, query a private server in our VPC in the cloud
Through the use of an Resolver Inbound endpoint
The on premise server will query its on-premise DNS resolvers
The on-premise DNS resolvers which would have a forwarding rule with the Route 53 target IP in it will forward it to the Resolver Inbound Endpoint in the private VPC
The Resolver Inbound Endpoint will forward the request to Route 53 resolver in the cloud which will lookup the query in the Private Hosted zone and return the information back downstream to the on-premise server
How can we have a private server in our VPC in the cloud, query an on premise server
Through the use of an Resolver Outbound endpoint
The cloud server will query its Route 53 resolver which will have a forwarding rule to forward the query to a target IP
Route 53 resolver will forward it to the Resolver Outbound Endpoint which will forward it to the On-premise DNS Resolvers
Which will forward it to the server
What are the types of resolver rules
Conditional forwarding rules: Forward DNS queries to target IPs
System rules: Override forwarding rules
Auto-defined system rules: Defines rules for selected domains like private AWS hosted zones
If multiple rules matched, Route 53 Resolver chooses the most specific match
Resolver Rules can be shared across accounts using AWS Resource Access Manager
