Route 53 Global DNS

Question 1

R53 Hosted Zone

Answer 1

DNS Data base for a domain

what the DNS system references Authoritative for a domain

Question 2

What is the resiliency of R53 ?

Answer 2

it’s Globally resilient with multiple DNS servers

Question 3

What does Host Zones contain ?

Answer 3

Host DNS records

e.g. A, AAAA, MX NS and TXT

Question 4

How many name servers are there per hosted zone ?

Answer 4

4 R53 name servers(NS) specific for the zone

accessible from public internet and VPC

Question 5

Private Hosted Zones

Answer 5

associated with VPC

only accessible in those VPCs

Question 6

Split View or Split Horizon DNS

Answer 6

overlapping public and private for public and internal uses with the same Zone name

Question 7

Route 53 Health Checks

Answer 7

health checks are separate from, but are used by records

checks if an record is healthy or unhealthy

in most cases an unhealthy record is not returned in queries

Question 8

Some benefits of R53 health checks

Answer 8

endpoint, cloudWatch alarms, check of checks calculated

Question 9

How often are checks by default

Answer 9

check every 30s (every 10s cost extra)

checks connection by TCP, HTTP/HTTPs with string matching

Question 10

A records

Answer 10

maps a Name to an Ip address

Question 11

CNAME records

Answer 11

maps a name to another name

e.i. www.catagram.io => catagram.io

Question 12

Limitation of Cnames

Answer 12

CNAME is invalid for naked/Apex domain

i.e. catagram.io

Question 13

Alias Record

Answer 13

maps a name to an AWS resource

can be used for both naked/apex and normal

no charge for Alias pointing at AWS resources

Question 14

Why user an Alias record over a CName record

Answer 14

Many AWS services us a DNS name (ELB)

Name : catatgram.io ==> ELB would be invalid

for AWS services the default is an Alias

Question 15

Route53 Simple Routing

Answer 15

simple routing doesn’t support health checks - all values are returned for a record when queried

Question 16

What case would simple routing be best ?

Answer 16

use simple routing when you want to route requests towards one service such as a web server

Question 17

Route53 Weighted Routing

Answer 17

Each record is return based on it’s record weight vs total weight

if a chosen record is unhealthy, the process of selection is repeated until a healthy record is chosen

Question 18

What does it mean when a record has a ‘0’ in Weighted Routing ?

Answer 18

A ‘0’ weight means a record is never returned unless all are ‘0’ then all are considered

Question 19

Route53 Failover Routing

Answer 19

if the target of the health check is ‘Healthy’ the primary record is used

if the target of the health check is unhealthy any queries return the secondary record of the same name

Question 20

When would you user weighted Routed ?

Answer 20

simple load balancing or testing new software versions

Question 21

What is the user case for Failover Routing ?

Answer 21

user when you want to configure active passive failover

a common architecture is to use failover for a ‘out of band’ failure / maintenance page for a service (e.g EC2/S3 )

Question 22

Route53 Multi Value Routing

Answer 22

Muli Value Routing supports Multiple records with the same name

Up to 8 ‘healthy ’ records are returned. if more exit 8 are randomly selected

each record has it’s own health check if a not healthy the record won’t be returned

Question 23

When would you user multi value routing ?

Answer 23

Multi value routing improves the availability

it is not a replacement for load balancing

Question 24

Route53 Latency-Based Routing

Answer 24

AWS maintains a database of latency between the users general location and the regions tagged in records

Latency-based Routing supports one record with the same name in each AWS region

The record returned is the one which offers the lowest estimated latency and is healthy

Question 25

Route53 Geolocation Routing

Answer 25

R53 checks for records 1) in the state, 2) in the country, 3) the continent and 4)(optionally) default specified by you

it returns the most specific record or ‘No Answer’

Question 26

When would you use Geolocation Routing ?

Answer 26

can be used for regional restriction, language specific content or load balancing across regional endpoints

Question 27

Route53 Geoproximity Routing

Answer 27

Routing is distance based including a bias

‘+’ or ‘-’ vais can be added to rules. ‘+’ increases a region size and decreases neighbouring regions

Question 28

Route 53 Registry only

Answer 28

The domain is register via R53 but the NS records for the domain are set to external hosted Name servers.

Not to common because most of Route53 benefit comes from hosting.

Question 29

Route53 Hosting Only

Answer 29

Creates a R53 public Hosted zone for the domain Pass the allocated NS details to the registrar

Question 30

Route 53 Both

Answer 30

Route 53 handles both registry and Hosting