DNS Record Types Explained: A, AAAA, MX, TXT, CNAME, NS & More

The Domain Name System (DNS) is the backbone of the internet. Every time you visit a website, send an email, or connect to any online service, DNS translates human-readable domain names into the numerical addresses that computers use to communicate. Understanding the different DNS record types is essential for anyone managing a domain, configuring email, or troubleshooting connectivity issues.

This guide covers the most important DNS record types, explains when and why you would use each one, and shows you how to check your own DNS configuration using our free tools.

A Records (Address Records)

The A record is the most fundamental DNS record type. It maps a domain name to an IPv4 address (the traditional 32-bit address format like 93.184.216.34). When someone types your domain into a browser, the DNS resolver looks up the A record to find the server's IP address and route the connection.

You can have multiple A records for the same domain, which is commonly used for load balancing or failover. The DNS resolver may return all addresses and let the client choose, or it may rotate through them using round-robin distribution.

AAAA Records (IPv6 Address Records)

AAAA records serve the same purpose as A records but for IPv6 addresses (the newer 128-bit format like 2606:2800:0220:0001:0248:1893:25c8:1946). As IPv4 address space continues to run out, IPv6 adoption is growing steadily. Publishing AAAA records alongside A records ensures your domain is accessible to both IPv4 and IPv6 clients.

Most modern hosting providers and CDNs assign both IPv4 and IPv6 addresses automatically. If your provider supports IPv6, make sure you have AAAA records configured to take advantage of the faster routing paths that IPv6 can offer.

MX Records (Mail Exchange)

MX records tell the internet where to deliver email for your domain. When someone sends an email to user@yourdomain.com, the sending server queries your MX records to find your mail server's address. Each MX record includes a priority value — lower numbers indicate higher priority.

Most domains have at least two MX records for redundancy: a primary server with priority 10 and a backup with priority 20. If the primary server is unavailable, email is delivered to the backup. Use our MX Lookup tool to check your domain's MX configuration and verify that your mail servers are reachable.

TXT Records (Text Records)

TXT records store arbitrary text data associated with your domain. While originally designed for human-readable notes, they have become critical for email authentication and domain verification. The most common uses include SPF records (specifying authorized mail servers), DKIM public keys (enabling email signature verification), DMARC policies (instructing receivers how to handle unauthenticated mail), and domain ownership verification for services like Google Workspace and Microsoft 365.

A single domain can have multiple TXT records, and each record can contain up to 255 characters per string (though multiple strings can be concatenated for longer values like DKIM keys). Check your TXT records with our DNS Lookup tool.

CNAME Records (Canonical Name)

A CNAME record creates an alias from one domain name to another. Instead of pointing to an IP address directly, a CNAME points to a different domain name, which then resolves to an IP through its own A or AAAA record. For example, you might point www.yourdomain.com as a CNAME to yourdomain.com, so both resolve to the same server.

CNAME records have important restrictions. You cannot place a CNAME at the zone apex (the bare domain without any subdomain prefix), and a domain with a CNAME cannot have any other record types at the same name. This is why some DNS providers offer proprietary solutions like ALIAS or ANAME records for apex domain aliasing.

NS Records (Name Server)

NS records specify which DNS servers are authoritative for your domain. When a resolver needs to look up any record for your domain, it first finds the NS records to know which servers to query. Your domain registrar typically sets NS records to point to your DNS hosting provider.

Most domains have at least two NS records for redundancy. If you change DNS providers (for example, moving from your registrar's DNS to Cloudflare), you update your NS records to point to the new provider's name servers. This change propagates globally within 24 to 48 hours.

SOA Records (Start of Authority)

Every DNS zone has exactly one SOA record. It contains administrative information about the zone, including the primary name server, the email address of the domain administrator (encoded in DNS format), the zone's serial number, and timing parameters for zone transfers and caching. The serial number is incremented every time a change is made, which helps secondary DNS servers know when to request an updated copy of the zone.

While you rarely need to edit SOA records manually, understanding them helps when troubleshooting DNS propagation issues. If changes are not propagating, checking the SOA serial number can confirm whether the update has been applied to the authoritative server.

PTR Records (Pointer Records)

PTR records are the reverse of A records. Instead of mapping a domain name to an IP address, they map an IP address back to a domain name. This reverse DNS lookup is critical for email deliverability — many mail servers reject messages from IPs that do not have a valid PTR record matching the sending domain.

PTR records are managed by the owner of the IP address block, which is usually your hosting provider or ISP, not your domain registrar. If you need to set up reverse DNS, contact your hosting provider. Use our Reverse DNS Lookup tool to check whether your sending IP has a properly configured PTR record.

How to Check Your DNS Records

Misconfigured DNS records can cause website outages, email delivery failures, and security vulnerabilities. Regular auditing is important, especially after making changes to your hosting, email provider, or domain settings.

Our DNS Lookup tool lets you query any record type for any domain instantly. For a comprehensive overview of your email-related DNS configuration, run a Domain Health Check to see your MX, SPF, DKIM, DMARC, and other records in a single report.

DNS and Email Security

DNS records are the foundation of email authentication. SPF, DKIM, and DMARC all rely on DNS to publish their policies and keys. Without correct DNS configuration, these protocols cannot function, leaving your domain vulnerable to spoofing and phishing attacks.

To learn how these email authentication protocols use DNS records to protect your domain, read our guide on SPF, DKIM & DMARC explained. For practical tips on improving your inbox placement rates, check out our email deliverability guide.