DNS 101

Question 1

top level domain name

Answer 1

.com
.edu
.uk
.au

Question 2

second level domain name

Answer 2

.co.uk
.gov.uk
.com.au

Question 3

SOA Record stores what?

Answer 3

name of server supplying data
administrator of zone
current version of data file
TTL for records
time to wait for secondary checking for updates, retrying zone transfer
time for secondary to expire or refresh its data

Question 4

NS records

Answer 4

Name Server records

Used by top level domains to direct traffic to the content DNS server

Question 5

A Records

Answer 5

Address record

Translates name to IP address

Question 6

TTL Record

Answer 6

length of time that DNS record is cached on resolving server or local PC

Question 7

CName

Answer 7

Canonical Name

resolves one domain to another

m.cloud.guru -> mobile.acloud.guru

Question 8

Alias Record

Answer 8

maps resource record sets in your hosted zone to ELBs, cloud front distributions or S3 buckets

works like a CNAME record, maps one DNS name to another

CANNOT be used for naked domain names (zone apex). That must always be an A Record or Alias

Question 9

Alias record set benefits

Answer 9

saves time because Route 53 automatically sees changes in record sets that the alias record set refers to

if IP on ELB changes, Route 53 will automatically reflect those changes in DNS

Question 10

Do ELB’s have IP address?

Answer 10

No. You use a DNS name for them

Question 11

Alias record vs CName

Answer 11

alias lets you resolve naked domain name to ELB

requests to Route53 are charged if you use CName, not if you use an Alias