DNS Record Types

Question 1

Resource Records (RR)

Answer 1

• The database records of domain name services

• Over 30 record types - IP addresses, certificates, host
alias names, etc

Question 2

Address Records (A) (AAAA)

Answer 2

• Defines the IP address of a host
  
  • This is the most popular query

• A records are for IPv4 addresses
• Modify the A record to change the host name to IP
address resolution

• AAAA records are for IPv6 addresses
  
  • The same DNS server, different records

Question 3

Canonical name records (CNAME)

Answer 3

• A name is an alias of another, canonical name

* One physical server, multiple services

Question 4

Service records (SRV)

Answer 4

• Find a specific service
• Where is the Windows Domain Controller? Where is
the instant messaging server? Where is the VoIP
controller?

Question 5

Mail exchanger record (MX)

Answer 5

• Determines the host name for the mail server - this isn’t an IP address; it’s a name

Question 6

Name server records (NS)

Answer 6

• List the name servers for a domain - NS records point to the name of the server

Question 7

Pointer record (PTR)

Answer 7

• The reverse of an A or AAAA record
  
  • Added to a reverse map zone file

A pointer (PTR) record is a type of Domain Name System (DNS) record that resolves an IP address to a domain or host name, unlike an A record which points a domain name to an IP address. PTR records are used for the reverse DNS lookup. Using the IP address, you can get the associated domain or host name.

Question 8

Text records (TXT)

Answer 8

• Human-readable text information
  
  • Useful public information

• SPF protocol (Sender Policy Framework)
• Prevent mail spoofing
• Mail servers check that incoming mail really did
come from an authorized host

• DKIM (Domain Keys Identified Mail)
• Digitally sign your outgoing mail
• Validated by the mail server, not usually seen by the
end user
• Put your public key in the DKIM TXT record