Route 53 Flashcards
What does DNS stand for?
Domain Name System
Translates the human friendly hostnames into the machine IP addresses
DNS
(DNS Terminologies) .. Amazon Route 53, GoDaddy, …
Domain Registrar
(DNS Terminologies) … A, AAAA, CNAME, NS, …
DNS Records
(DNS Terminologies) … contains DNS records
Zone File
(DNS Terminologies) … resolves DNS queries (Authoritative or Non-Authoritative)
Name Server
(DNS Terminologies) … .com, .us, .in, .gov, .org, …
Top Level Domain (TLD)
(DNS Terminologies) … amazon.com, google.com, …
Second Level Domain (SLD)
A highly available, scalable, fully
managed and Authoritative DNS
Amazon Route 53
The customer (you)
can update the DNS records
Authoritative DNS
Is a Domain Registrar
Amazon Route 53
Does Amazon Route 53 have the ability to check the health of your resources?
YES
The only AWS service which provides 100% availability SLA
Amazon Route 53
How you want to route traffic for a domain
Route 53 - Records
What does each Record contain? (5)
- Domain/subdomain Name – e.g., example.com
- Record Type – e.g., A or AAAA
- Value – e.g., 12.34.56.78
- Routing Policy – how Route 53 responds to queries
- TTL – amount of time the record cached at DNS Resolvers
(must know)A /AAAA / CNAME / NS
(advanced)CAA/DS/MX/NAPTR/PTR/SOA/TXT/SPF/SRV
DNS record types Route 53 supports
Must know Route 53 RecordTypes
A
AAAA
CNAME
NS
maps a hostname to IPv4
Route 53 – Record Types
A
maps a hostname to IPv6
Route 53 – Record Types
AAAA
maps a hostname to another hostname
Route 53 – Record Types
CNAME
For a CNAME record type, the target is a domain name which must have an _____ or ______ record
Route 53 – Record Types
A
AAAA
Can’t create a ______ record for the top node of a DNS namespace (Zone Apex)
Route 53 – Record Types
CNAME
Name Servers for the Hosted Zone
Route 53 – Record Types
NS
Control how traffic is routed for a domain
Route 53 – Record Types
NS
A container for records that define how to route traffic to a domain and its subdomains
Hosted Zones
2 types of Hosted Zones
Public Hosted Zones
Private Hosted Zones
contains records that specify how to route traffic on the Internet (public domain names) application1.mypublicdomain.com
Public Hosted Zones
contain records that specify how you route traffic within one or more VPCs (private domain names) application1.company.internal
Private Hosted Zones
How much do you pay per month per hosted zone??
$0.50
What does TTL stand for??
Time To Live
What are Records TTL
The time the records is on the cache
TTL is mandatory for each DNS record except for which type of Record?
Alias Records
Points a hostname to any other hostname. (app.mydomain.com => blabla.anything.com)
CNAME
ONLY FOR NON ROOT DOMAIN (aka. something.mydomain.com)
CNAME
Points a hostname to an AWS Resource (app.mydomain.com => blabla.amazonaws.com)
Route 53 – Alias Records
- Free of charge
- Native health check
Alias
- Maps a hostname to an AWS resource
- An extension to DNS functionality
- Automatically recognizes changes in the resource’s IP addresses
Alias Records
Unlike CNAME, it can be used for the top node of a DNS namespace (Zone Apex)
Alias Records
is always of type A/AAAA for AWS resources (IPv4 / IPv6)
Alias Records
You can’t set the TTL
Alias Records
What are the Alias Records Targets
- Elastic Load Balancers
- CloudFront Distributions
- API Gateway
- Elastic Beanstalk environments
- S3 Websites
- VPC Interface Endpoints
- Global Accelerator accelerator
- Route 53 record in the same hosted zone
Can set an ALIAS record for an EC2 DNS name?
NO
Define how Route 53 responds to DNS queries
Routing Policies
Route 53 Supports the following Routing Policies (8)
- Simple
- Weighted
- Failover
- Latency based
- Geolocation
- Multi-Value Answer
- Geoproximity (using Route 53 Traffic Flow feature)
- IP based
- Typically, route traffic to a single resource
- Can specify multiple values in the same record
- If multiple values are returned, a random one is chosen by the client
- When Alias enabled, specify only one AWS resource
- Can’t be associated with Health Checks
Routing Policies – Simple
- Control the % of the requests that go to each specific resource
- Assign each record a relative weight:
- 𝑡𝑟𝑎𝑓𝑓𝑖𝑐(%)= !”#$%&’()*+,”-#’#-)”-().
/01 (‘ *22 &%” 3”#$%&+ ‘() *22 )”-().+ - don’t need to sum up to 100
- DNS records must have the same name and type
- Can be associated with Health Checks
- Use cases: load balancing between regions, testing new application versions…
- Assign a value of 0 to a record to stop sending traffic to a resource
- If all records have a value of 0, then all records will be returned equally
Routing Policies – Weighted
- Redirect to the resource that is close to us
- Is based on traffic between users and AWS Regions
- Germany users may be directed to the US
- Can be associated with Health Checks (has a failover capability)
Routing Policies – Latency-based
HTTP Health Checks are only for _______?
public resources
What are 3 ways that a Health Checks can monitor?
Endpoints
Other Health Checks (Calculated Health Checks)
CloudWatch Alarms
Are Health Checks integrated with CloudWatch metrics??
YES
About _______ global health checkers will check the endpoint health
15
For a Health check monitoring an Endpoint, What is the Healthy/UnhealthyThreshold by default?
3
For a Health check monitoring an Endpoint, what is the monitoring interval and what could you set it at for a higher cost??
30 secs
10 secs
For a Health check monitoring an Endpoint, what protocols are supported??
HTTP, HTTPS, andTCP
If > _______% of health checkers report the endpoint is healthy, Route 53 considers it Healthy. Otherwise, it’s Unhealthy
18
Health Checks pass only when the endpoint responds with the ______ and _____ status codes
2XX
3XX
Health Checks can be setup to pass / fail based on the text in the first ________ of the response
5120 bytes
Do you need to configure your router/firewall to allow incoming requests from Route 53 Health Checkers
YES
- Combine the results of multiple Health Checks into a single Health Check
- You can use OR, AND, or NOT
Calculated Health Checks
Calculated Health Checks can monitor up to ______ Child Health Checks
256
Can you specify how many of the health checks need to pass to make the parent pass???
YES
- Route 53 health checkers are outside the VPC
- They can’t access private endpoints (private VPC or on-premises resource)
- You can create a CloudWatch Metric and associate a CloudWatch Alarm, then create a Health Check that checks the alarm itself
Health Checks for Private Hosted Zones
- Different from Latency-based!
- This routing is based on user location
- Specify location by Continent, Country or by US State (if there’s overlapping, most precise location selected)
- Should create a “Default” record (in case there’s no match on location)
- Use cases: website localization, restrict content distribution, load balancing, …
- Can be associated with Health Checks
Routing Policies – Geolocation
- Route traffic to your resources based on the geographic location of users and resources
- Ability to shift more traffic to resources based on the defined bias
- To change the size of the geographic region, specify bias values:
- To expand (1 to 99) – more traffic to the resource
- To shrink (-1 to -99) – less traffic to the resource
- Resources can be:
- AWS resources (specify AWS region)
- Non-AWS resources (specify Latitude and Longitude)
- You must use Route 53 Traffic Flow to use this feature
Routing Policies – Geoproximity
- Use when routing traffic to multiple resources
- Route 53 return multiple values/resources
- Can be associated with Health Checks (return only values for healthy resources)
- Up to 8 healthy records are returned for each Multi-Value query
- Multi-Value is not a substitute for having an ELB
Routing Policies – Multi-Value
- Routing is based on clients’ IP addresses
- You provide a list of CIDRs for your clients and the corresponding endpoints/locations (user-IP-to-endpoint mappings)
- Use cases: Optimize performance, reduce network costs…
- Example: route end users from a particular ISP to a specific endpoint
Routing Policies – IP-based Routing
