Route 53 Flashcards
What is Route 53?
What is a DNS?
What are the 4 most common records in AWS and what do they map?
Describe the flow for locating a server using a DNS?’
What types of domains can route 53 use?
Route 53 is a managed domain name system
DNS is a colleciton of rules and records which helps clients understand how to reach a server through its domain name
A: Hostname to IPv4
AAAA: Hostname to IPv6
CNAME: Hostname to Hostname
Alias: Hostname to AWS resource
A request will be sent from the web browser to a DNS service such as route 53. This request will contain the domain name. The DNS will respond to the request with an IP address of the server that that domain name belongs to. The web browser will then make a request to that IP address
Public domain names that you own. Ex. application1@publicdomain.com or private domain names that can be resolved by your instances VPCs. Ex application1.company.internal
What are the advanced features of Route53?
How much does Route 53 cost
Load balancing, health checks, routing policy
$.50 per hosted zone. There is no free tier
What is a DNS record TTL?
What are some of the effects of having a high TTL eg 24h?
What are some of the effects of having a low TTL ex 60 seconds?
A DNS record TTL will cashe the record from the DNS service for a defined period of time. This will help decrease the load on the DNS.
Less traffic on the DNS
Possibly outdated records
More traffic to DNS
Records are outdated for less time
Easy to change records
Does a CNAME work for a root domains or sub domains?
Does an Alias work for root domains or sub domains?
What does an Alias point to?
How much does an alias cost?
Which provides a healthcheck a CNAME or an Alias?
Sub-domains
Both
An AWS resources. Ex blabla.aws.com
Free
Alias
What is a simple routing policy?
Does a simple routing policy have health checks?
What happens if multiple values are returned in the record?
The browser makes a request to the DNS and the DNS returns a record.
No
If multiple values are returned, a random one is chose by by the client.
What is a weighted policy?
How does a weighted routing policy work?
Why is a weighted routing policy useful?
Can a weighted routing policy be associated with a health check?
It controls the percentage of the requests that go to a specific endpoint.
Percentages are assigned to each record, then the DNS will return that record the given percentage amount of time.
To test a percentage of traffic on a new app version.
To split traffic between regions.
Yes
How do you add multiple records to a record set?
By giving them the same name (subdomain)
How does a latency routing policy work?
What is a latency routing policy helpful?
How is latency evaluated?
How does a latency routing policy know which AWS region an IP address is located in?
If your application is hosted in multiple AWS Regions, you can improve performance for your users by serving their requests from the AWS Region that provides the lowest latency. A latency routing policy will redirect to the server that has the least latency close to us.
When you are concerned with latency.
Latency is evaluated in terms of a user to designated AWS Region.
When you create the record, you input the region of the IP address
What is a DNS health check
What determines if a health check is healthy or unhealthy?
What are the default and fast health check intervals?
How many healthecks are created by default and how many requests will you receive?
What protocols do health checks support?
What can health checks be integrated with? What can they be linked with?
A health check query. If the query determines that the instance is unhealthy route 53 will not send traffic to that instance.
Three passed or failed checks.
Default: 30 seconds,
Fast: 10 with one request every 2 seconds
AWS is sending about 12 requests per interval, so there’s going to be a request bout every 2 seconds or every second depending on the helthcheck speed
TCP, HTTP, HTTPS
CloudWatch, Route53 queries
Describe how a failover routing policy works.
What is mandatory for a failover routing policy?
How many routes are needed for a failover routing policy?
Does the secondary record need to be associated with a health check?
A routing policy that takes affect when a health check fails
I primary record and a secondary record (The records should point to a primary and secondary disaster recovery site). And a health check
2
No
What is a Geo Location routing policy
What are the 3 types of locations you can choose?
What must be defined for a Geolocation policy?
A geo location policy chooses the the DNS record to return based on a users geo location. (This is not their region, it’s their actual location like Ireland). When defining a geo location policy you should also define
Continent, country, default
A default location otherwise no result will be returned.
What is geoproximity routing.
In Geo-proximity routing. What are the 2 ways you can specify resources?
It essentially allows you to define a weighted bias to resources based on a users proximity to that resource and the weight assigned to is. For example, if you’re a little further away from one resource than another, but the more distant resource has a higher bias/weight, route 53 will return the record for the more distant resource.
AWS resources by region and Non-AWS resources by lat /long
What is a multi-value routing policy?
How many records and be returned?
Where does the load balancing happen for this type of record.
It’s basically an improvement on the simple routing policy that allows you to rout traffic to multiple resources and allows health checks.
Up to 8 healthy records.
What is a registrar
How can you use a 3rd party domain on Route53?
An organization that manages the reservation of internet domain names.
Create a hosted zone in Route53, then update your name server records on the 3rd party website to use the Route 53 name servers.
