DNS / Route 53

Question 1

Why is it called Route 53?

Answer 1

Think Route 66, in that it goes aross everything (one side of the country to the other) DNS is on port 53

Question 2

What does DNS stand for?

Answer 2

Domain Name System

Question 3

What is DNS used for?

Answer 3

DNS is used to convert human-friendly domain names into IP addresses

Question 4

What does IP stand for?

Answer 4

Internet Protocol

Question 5

What does an IP address do?

Answer 5

IP addresses are used by computers to identify each other on the network

Question 6

What is a Top Level Domain?

Answer 6

The part of a website that goes after the last “.” (e.g. .com, .edu, .gov)

Question 7

What is a second level domain name?

Answer 7

The second-to-last work in a domain name (optional)

e.g. the “co” in .co.uk

Question 8

What does IANA stand for?

Answer 8

Internet Assigned Numbers Authority

Question 9

How are top level domain names controlled?

Answer 9

They are controlled by IANA in a root zone database, which is a database of all available top level domains.

Question 10

What is the key purpose of domain registrars?

Answer 10

Ensuring that all names in a given domain are unique.

Question 11

What does SOA stand for?

Answer 11

Start Of Authority Record

Question 12

What info is contained in an SOA?

Answer 12

• The name of the server that supplied data for the zone
• Administrator of the zone
• Current version of the data file
• default # of seconds for the TTL file on resource records

Question 13

What does NS stand for?

Answer 13

Name Server Records

Question 14

What is the purpose of an NS Record?

Answer 14

They are used by Top Level Domain servers to direct traffic to the Content DNS server which contains the authoritative DNS records.

Question 15

What does the “A” stand for in “A” Record?

Answer 15

Address

Question 16

What does an “A” Record do?

Answer 16

The A record is used by the computer to translate the name of the domain to an IP address

Question 17

In the context of DNS, why is TTL important?

Answer 17

• TTL is the length of time that a DNS record is cached on either the Resolving Server or the user’s own local PC.
• The lower the TTL, the faster changes to DNS records take to propogate throughout the internet.

Question 18

What does CName stand for?

Answer 18

Canonical Name

Question 19

What does a CName do?

Answer 19

A CNAME is used to resolve one domain name to another

(Imagine looking in the phone book for BATMAN -> See West, Adam)

Question 20

What is an Alias Record?

Answer 20

Alias Records are used to map resource record sets in your hosted zone to Elastic Load Balancers, CloudFront Distributions, or S3 buckets that are configured as websites.

Question 21

What is a naked domain name?

Answer 21

a DNS server name that doesn’t have the “www” or any other subdomains

Question 22

What is a zone apex record?

Answer 22

A DNS name that doesn’t have “www” or any of the other subdomains

Question 23

What is the key difference between an Alias Record and a CName?

Answer 23

While both are used to map a DNS name to another, CNames cannot be used for naked domain names

Question 24

Do Elastic Load Balances have pre-defined IPv4 addresses?

Answer 24

No, you resolve to them using a DNS name

Question 25

On the exam, given the choice between an Alias Record and a CName, which should you pick?

Answer 25

Alias Records (CNAMEs can’t handle zone apex records)

Question 26

What does the MX stand for in MX Record?

Answer 26

Mail Exchanger

Question 27

What does the PTR stand for in PTR Record?

Answer 27

Pointer

Question 28

At a high level, what does a PTR Record do?

Answer 28

Maps an IP address to a domain/host name

(Think inverse of an A record)

Question 29

Can you buy domain names directly from AWS?

Answer 29

Yes, but it can take up to 3 days to register depending on the circumstances.

Question 30

What are the common DNS types?

Answer 30

• SOA Records
• NS Records
• A Records
• CNAMES
• MX Records
• PTR Records

Question 31

What is the limit to the number of domain names you can manage using Route53?

Answer 31

default limit is 50 domain names, but this can be increased by contacting AWS Support

Question 32

Can an Alias record point to AWS Resources that are hosted in other accounts?

Answer 32

Yes, by manually entering the ARN

Question 33

There is a website hosted in AWS that might get a lot of traffic over the next few weeks. If the application experiences a natural disaster at this time, what should be done to reduce potential disruption to users?

Answer 33

Use Route53 to route requests to another instance in a different region