Route 53

Question 1

What is a DNS Hosted Zone?

Answer 1

DB containing DNS records for a domain that’s been created/registered.

These can be Public (Internet) or Private (VPC).

Question 2

Is R53 Global, Region, or AZ resilient?

Answer 2

Globally Resilient

Question 3

DNS Flow:

Answer 3

1. Client queries “sports.com”
2. DNS query gets sent to the NAME SERVERS (4) for that particular domain (these are Authoritative in nature for the sports.com domain)
3. R53 Name Servers will then locate the “sports.com” ZONE FILE/DB to get to where the Hosted Zone is stored (Hosted Zone is just a DB containing DNS records)
4. Once the data is accessed, it’s passed back through the R53 name servers all the way back to the DNS client

Question 4

What is a R53 Health Check?

Answer 4

Enabled R53 to determine the “health” of a particular target (IP address) for an associated domain.

If a domain has 1 x record with 3 x IP’s, then it can determine which IP (if any) is “unhealthy” and not return that to the client requester.

Without this, all 3 get returned and the client attempts to connect to one of them at random.

Question 5

What is the interval(s) for R53 health checks?

Answer 5

30 sec (default)

10 sec ( for added cost)

Question 6

Six R53 Routing Policies

Answer 6

1. Simple
2. Failover
3. Weighted
4. Latency-Based
5. Geolocation
6. Multi-Value

Question 7

Simple R53 Routing Policy (this is default)

Answer 7

Hosted Zone = 1 record with 3 IP targets. All 3 are sent back to client and one is chosen at random.

This is the only one that doesn’t feature Health Checks

Question 8

Failover R53 Routing Policy

Answer 8

TWO records with the same name i.e Primary and Secondary record for a domain in A/S fashion.

Primary = IP address
Secondary = S3 bucket

A Health Check is associated with the PRIMARY record, which is what is the default record when queried.

Question 9

Weighted R53 Routing Policy

Answer 9

Multiple records with the same name in a Hosted Zone.

Each record gets a weighted value and is sent back to client based on that value.

Example: IP#1 gets returned 90% of the time, whereas IP#2 get’s returned 10% of the time

If a record has a bad health check, it does the process again and again and again until a record with a good health check is sent back

Question 10

Latency-Based R53 Routing Policy

Answer 10

Multiple records with the same name in a Hosted Zone.

For each record, you specify a region that the record corresponds to (EX = US-East-1) - basically gives R53 awareness of where the infra. is stored.

When a query comes in, R53 knows which region it’s coming from and can cross-reference the latency between the client and available regions that the record is available and picks the one with the lowest latency.

Question 11

Geolocation R53 Routing Policy

Answer 11

Multiple records with the same name in a Hosted Zone - but you can also add a location field i.e a particular STATE, COUNTRY or CONTINENT.

Ex - request comes from Texas, so R53 tries to resolve the record using DNS within the United States; if not the state, it checks the country, then it checks/tries the continent.

ONLY returns RELEVANT records to customers from the same Geo-area, not the CLOSEST records.

Will try to resolve/return records to clients from within the same geographical area.

Question 12

Multi-Value R53 Routing Policy.

How many values (IP addresses) can be in a record pool for options?

Answer 12

Multiple records with the same name in a Hosted Zone, where each value has its own Health Check. Any record marked unhealthy will be removed from the response to the query.

When queried - up to (8) healthy records are returned.

Mix of Simple and Failover routing.

• Improves reliability compared to Simple
• Alternative to Failover when you have multiple records but don’t want the complexity of overhead from weighted routing

Question 13

What is the difference between a Public and Private DNS Hosted Zone?

Answer 13

** Private Hosted Zone = responding to queries for domains within a VPC(s)

** Public Hosted Zone = responding to queries for domains over the internet

Question 14

What are the 3 types (where you can place) of R53 Health Checks?

Answer 14

Endpoint checks
CloudWatch Alarm checks
Checks of other checks

Question 15

REVIEW:

Answer 15

→ DNS “A” Records map a NAME to an IP address : sports.io&raquo_space; 1.3.3.7

→ DNS CNAME Records map a NAME to another NAME : www.sports.io&raquo_space; sports.io

Question 16

Can a CNAME Record be used to map to the Apex of a domain (Naked domain)?

Answer 16

NO.

CNAME can only be mapped to normal records

Question 17

What is the difference between CNAME and ALIAS DNS Records?

Answer 17

ALIAS records map a NAME to AWS resources, whereas CNAME records map a NAME to another NAME.

ALIAS can map to both an Apex domain or a Regular domain, whereas CNAME can’t map to an Apex domain.

Question 18

What is R53 Geo-Proximity Routing policy?

Does it work for non-AWS resources?

Answer 18

Aims to provide records as close to your customers as possible. Similar to Latency-Based routing, but instead of latency, this is focused on DISTANCE.

Yes - for non-AWS resources yo use geo-coordinates instead of AWS Region.

Question 19

How can you manipulate a Geo-Proximity Routing policy?

Answer 19

You can define a “Plus or Minus (+ or -) Bias:

§ Increases a region size and decreases a neighboring region

§ You can optionally choose to route MORE traffic or LESS traffic to a specific region based on a Bias

§ More surrounding countries will route to a specific region