2.6 - DNS Configuration

Question 1

What is DNS?

Answer 1

DNS is the domain name system that converts fully qualified domain names into IP addresses.

Question 2

Is DNS a standalone server?

Answer 2

No, DNS is a distributed system with multiple servers across the internet working on a hierarchy.

Question 3

How many root server clusters are there?

Answer 3

There are 13 root server clusters, consisting of over 1,000 different servers.

Question 4

What are generic top-level domains?

Answer 4

These are domains like .com, .org, .net, etc.

Question 5

What are country-level top-level domains?

Answer 5

Domains specific to countries, like .us (USA), .ca (Canada), and .uk (UK).

Question 6

What does the dot at the end of a domain name represent?

Answer 6

The dot at the end designates the end of a fully qualified domain name.

Question 7

What is an example of a hierarchical domain structure?

Answer 7

For example, www.professormesser.com with mail.professormesser.com for mail servers.

Question 8

What command can you use to see DNS translation results?

Answer 8

The dig command can be used, e.g., ‘dig www.professormesser.com’.

Question 9

What does the ANSWER SECTION in dig command results show?

Answer 9

It shows the IP addresses associated with the requested domain name.

Question 10

What is nslookup?

Answer 10

A command to query DNS servers for IP addresses, similar to dig.

Question 11

What are resource records in DNS?

Answer 11

These are records like IP addresses, certificates, host names, etc., used in DNS.

Question 12

Why are DNS servers critical?

Answer 12

DNS servers translate domain names into IP addresses; without them, websites can’t be accessed.

Question 13

What is an A record?

Answer 13

An address record mapping a fully qualified domain name to an IPv4 address.

Question 14

What is a quad A record?

Answer 14

An address record mapping a fully qualified domain name to an IPv6 address.

Question 15

What is an MX record?

Answer 15

A mail exchanger record specifying where emails for a domain should be delivered.

Question 16

What is a TXT record?

Answer 16

A text record in DNS used for purposes like verification and email security.

Question 17

What is an SPF record?

Answer 17

A Sender Policy Framework record listing authorized email servers for a domain.

Question 18

What is a DKIM record?

Answer 18

A Domain Keys Identified Mail record that provides a digital signature for outgoing emails.

Question 19

What is DMARC?

Answer 19

Domain-based Message Authentication, Reporting, and Conformance; it specifies what to do with unverified emails.

Question 20

What does a DMARC record specify?

Answer 20

It specifies actions like accepting, spamming, or rejecting unverified emails, and where to send reports.