DNS Records (Resource Record) Basics
DNS Records are data items stored in DNS Name Servers. They define various pieces of information about a domain name, including server addresses, services, and security information, providing the answers to DNS queries.
1. Core Components of a DNS Record
Every DNS record contains the following main fields:
| Field | Description |
|---|---|
| Name | The domain name or subdomain to which the record applies. |
| Type | The kind of record (e.g., A, MX, CNAME, etc.). |
| Class | The network class (usually fixed to IN for Internet). |
| TTL (Time To Live) | The time (in seconds) that resolvers are allowed to cache this record's information. |
| Value (RDATA) | The actual data of the record (an IP address, another domain name, text, etc.). |
2. Key DNS Record Types
The 5 most frequently used DNS record types are:
| Type Name | Type | Role | Value (RDATA) |
|---|---|---|---|
| Address Record | A (Address) | Translates a domain name to an IPv4 address. This is the most fundamental record. | An IPv4 address like 192.0.2.1 |
| Address Record | AAAA (Quad-A) | Translates a domain name to an IPv6 address. | An IPv6 address like 2001:db8::1 |
| Canonical Name | CNAME | Aliases one domain name to another domain name. (e.g., mapping www.example.com to example.com) |
The target domain name |
| Mail Exchanger | MX | Specifies the mail server responsible for handling email for the domain. | The mail server's domain name and a priority number |
| Text Record | TXT | Used to store free-form text data, often for domain verification, anti-spam information (like SPF, DKIM), or security policies. | An arbitrary text string |