Difficulty:Beginner
Applies to:DNS

What are DNS records? 

DNS records are used to direct domains to IP addresses, each record type have their own capabilities.

Types

A -

This record communicates what IP address is used with a domain name or subdomain.
 
NAME                       TYPE   VALUE -------------------------------------------------- foo.example.com.        A      198.181.125.248 
 
Once inputted accessing foo.example.com will direct to 198.181.125.248
 This is only compatible with IPv4
AAAA – This record is exactly the same as an A record but uses IPv6.
CNAME – This record is similar to an A record; the difference is it is mainly used when you do not have an IP to use. CNAMEs use domain names to map the domain across.
 
NAME                           TYPE      VALUE -------------------------------------------------- bar.example.com.        CNAME     foo.example.com.
 
The above example shows that bar.example.com will direct to foo.example.com
Also known as Canonical Name
MX – This record is used to route mail to their mail servers using IPs. Priority is used to specify the order of the records normally formatted in variables of 5.
 
NAME                         TYPE      PRIORITY     VALUE ----------------------------------------------------------- mx.example.com.         MX          5               mailserver.com. 
 
TXT – This record is mainly used for authentication purposes, normally a long string of text is used to authenticate web programmes and services.
 
NAME                       TYPE       VALUE ------------------------------------------------------------ example.com.            TXT        google-site-verification=wwi34n45bh@
SPF – This is a type of TXT record which is used to verify that mail should be sent from the IP or server it lists. This is used to help defeat spoofing as it can verify the where it is coming from.
 
NAME                       TYPE       VALUE ------------------------------------------------------------ example.com.            TXT        v=spf1 mx:example.com -all   
 
There are multiple parts of an SPF record:

Components

Description

@

In a DNS file, the @ symbol is a placeholder used to demonstrate the current domain

v=spf1

Identifies the TXT record as an SPF record

a

Authorises the host server shown in the domain's A record to send e-mail

~all

Displays that this list is all inclusive, and no other servers are allowed to send e-mail
Also known as Sender Policy Framework
 
PTR – Used to confirm that the domain is connected to the IP it lists. Ideally used for outgoing mail servers as mail providers are less likely to reject mail servers with validated PTR records.
 
NAME                       TYPE   VALUE -------------------------------------------------- 1.0.168.192.in-addr.arpa    PTR    example.com.
Also known as Reverse DNS