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Email Protocols

DNS Record

A database entry that provides information about a domain, essential for email authentication and routing.

Definition

DNS (Domain Name System) records are entries in the domain name system that provide information about a domain. For email, critical DNS records include MX (mail exchange) for routing, TXT records for SPF and DKIM authentication, and CNAME records for domain verification. Proper DNS configuration is essential for email deliverability.

Why It Matters

Incorrect or missing DNS records cause authentication failures, delivery problems, and security vulnerabilities. Email providers check your DNS records to verify you are authorized to send from your domain. Without proper records, your emails may be rejected or marked as spam.

How It Works

When a server receives your email, it queries DNS for your domain's records. It checks MX records to route mail, SPF records to verify sending authorization, and DKIM records to verify signatures. These lookups happen in milliseconds and affect whether your email is accepted.

Example

Common email-related DNS records:

MX Record: Routes email to your mail server Priority 10: mail.example.com

SPF Record (TXT): Lists authorized senders v=spf1 include:_spf.google.com include:sendgrid.net ~all

DKIM Record (TXT): Contains public key for signature verification selector._domainkey.example.com v=DKIM1; k=rsa; p=[public key]

DMARC Record (TXT): Authentication policy _dmarc.example.com v=DMARC1; p=quarantine; rua=mailto:[email protected]

Best Practices

  • 1Verify all email-related DNS records are correctly configured
  • 2Use DNS checking tools to validate your setup
  • 3Keep track of TTL (time-to-live) values when making changes
  • 4Document your DNS configuration for troubleshooting
  • 5Update DNS when changing email providers or adding new services

Frequently Asked Questions

DNS changes typically propagate within 15 minutes to 48 hours depending on TTL values and caching. For email changes, plan for up to 24 hours and avoid major campaigns during this period.

Use tools like MXToolbox, Google Admin Toolbox, or command-line tools like dig and nslookup. These show your current DNS configuration and identify issues.