DNS, Caching, Performance Optimization Flashcards
Hosted Zone
represents a set of records that belong to a domain that allow DNS to query for the IP address that aligns to the domain
Route53
Advanced DNS service
List Route53 Routing Policies
Simple
Failover
Geolocation
Geoproximity
Latency
Multivalue answer
Weighted
IP-Based
Simple Routing Policy
Simple DNS response providing the IP address associated with a name
Responds to DNS queries
Configure DNS records with domain name to multiple/single IP with TTL
Failover Routing Policy
If primary is down (based on health checks), routes to secondary destination
has a primary and secondary record type
Geolocation Policy
Uses geographic location of client in e.g. Europe to route you to the closest region
has name, type, value, health, and geolocation
Health checks are optional
Geoproximity Policy
Routes you to the closest region within a geographic area (can apply bias)
create a policy in traffic flow - specify coordinates to route to endpoints that include CloudFront, Elastic Beanstalk, S3, and IP addresses
use bias value to load balance between regions
Latency Policy
Directs you a region based on the lowest latency route to resources (routes by lowest latency)
has name, value, record type, health id and region
value can be load balancer or IP
Health checks are optional
Multivalue answer Policy
Returns several IP addresses and functions as a basic load balancer
Health check returns only healthy records
Weighted Policy
Uses the relative weights assigned to resources to determine which to route to
Configure DNS records with domains, IP and weight so that traffic is routed to be proportional to the record according to the configured weight
Weights can be between 0 -255 (simplified values) or percentages
Health checks are optional
IP Based Policy
Uses the IP addresses of clients to make routing decisions
Create CIDR collections = are used to define IP addresses and CIDR blocks of clients
Routing rules can be created to route based on CIDR collection
Top Level domain
subdomain
hostname
last word of a Fully qualified domain name, e.g. com
Subdomains are everything outside of the top level e.g. example.com - example is subdomain; subdomain is subdivision of a domain name for organizing a set of related resources or services
first word in domain name (www.example.com)
Route 53 Features
Domain name registration
Hosted zones (support DNS resolution, query)
Health checks
Traffic flow
A record type
maps a domain name to an IP address
CNAME record type
maps a domain name to another domain name
MX records
returns mail servers for domain name
TXT records
Associated text with a domain name (used for verification/authz)
SRV records
maps a domain name to a specific service or protocol
NS
specifies the authoritative DNS server for a particular domain
SOA
Start of Authority records stores important information about a domain
Public vs Private hosted zones
public hosted zone is accessible to the internet; created by default for new domain registrations
private zones can be used for internal AWS routing within you account
Route53 health checks
perform health checks against EC2 instances, load balancers, and other IP endpoints
enable active passive failover - send traffic to other resources based on health
Route53 Resolver
Allows Route53 to be forward request to another DNS server for DSN resolution
Route53 Resolver Outbound Endpoint - describe configuration and provide typical use case
DNS server in corporate data center
VPN connects VPC to coporate data centet via customer gateway and VGW
Route53 is configured with Outbound Endpoint (in VPC subnets where DNS query could come from?), so that when AWS resource request item in corporate data center AWS will look up the record in Route53, Route53 will return the Outbound Endpoint location, which will forward to the corporate DNS for resolution
