What Are DNS Records?
DNS (Domain Name System) records are instructions stored in DNS servers that map human-readable domain names to machine-readable information — IP addresses, mail server locations, verification tokens, and security policies.
When you visit a website or send an email, DNS records are the phonebook entries that tell your computer exactly where to go and what rules to follow.
How DNS Lookup Works
- You type
freemailtools.comin your browser - Your computer asks a recursive DNS resolver (usually from your ISP or 1.1.1.1) for the IP address
- The resolver asks the root nameservers which servers are authoritative for
.comTLDs - The resolver asks those TLD nameservers which servers are authoritative for
freemailtools.com - The resolver asks the authoritative nameservers for the A record of
freemailtools.com - The answer is returned and cached for the TTL duration
- Your browser connects to the returned IP address
This entire process typically takes 20–100ms on a first query, and is served from cache in under 1ms on subsequent queries within the TTL window.
DNS Record Types Explained
A Record — IPv4 Address
Maps a domain/subdomain to an IPv4 address.
Use case: Points a domain or subdomain to a web server.
AAAA Record — IPv6 Address
Maps a domain to an IPv6 address.
Use case: IPv6 connectivity for modern networks.
CNAME Record — Canonical Name
Creates an alias from one domain name to another.
Use case: Point www to the apex domain. Can't be used at the apex domain itself (use ALIAS or ANAME instead).
MX Record — Mail Exchange
Specifies the mail servers that receive email for a domain. Lower priority number = higher preference.
Use case: Email routing. Without MX records, email cannot be delivered to your domain.
TXT Record — Text
Stores arbitrary text strings in DNS. Used for domain verification, email authentication, and many other purposes.
Use case: SPF records, DMARC records, domain ownership verification, DKIM public keys.
NS Record — Name Server
Specifies which DNS servers are authoritative for the domain.
Use case: Delegates DNS authority to your DNS provider. Must have at least two NS records for redundancy.
SOA Record — Start of Authority
Contains administrative information about a DNS zone.
Includes: primary nameserver, admin email, serial number, refresh/retry/expire/minimum TTL values.
PTR Record — Pointer (Reverse DNS)
Maps an IP address back to a domain name. The inverse of an A record.
Use case: Used by receiving mail servers to verify that the IP address sending mail matches the hostname in the HELO/EHLO greeting. Missing or mismatched PTR records can cause emails to be flagged as spam.
TTL — Time to Live
Every DNS record has a TTL value in seconds. This tells resolvers how long to cache the record before re-querying the authoritative server.
- Low TTL (60–300s): Changes propagate quickly, but adds more load to DNS servers
- High TTL (3600–86400s): Fewer DNS queries, but changes take longer to propagate globally
Best practice: Before making DNS changes, lower TTL to 300 seconds at least 24 hours in advance. After confirming the change, restore the TTL.
DNS Tools
Use our free DNS toolkit to look up any record type for any domain:
- DNS Lookup — Full DNS health analysis
- DNS Propagation Checker — See if changes have propagated globally
- A Record Lookup, AAAA, MX, TXT, CNAME, NS, SOA, PTR
- Reverse DNS Lookup — IP to hostname