DNS Record Checker - Verify SPF, DKIM, DMARC & More

Email authentication is critical for protecting your domain from spoofing and phishing attacks. Three key protocols work together to verify email legitimacy:

SPF (Sender Policy Framework)

SPF records specify which mail servers are authorized to send email on behalf of your domain. When a recipient server receives an email claiming to be from your domain, it checks your SPF record to verify the sending server is authorized.

A typical SPF record might look like:

v=spf1 include:_spf.google.com include:spf.protection.outlook.com ~all

This example authorizes Google and Microsoft mail servers while using a "soft fail" (~all) for unauthorized senders.

DKIM (DomainKeys Identified Mail)

DKIM adds a digital signature to email headers, allowing receiving mail servers to verify that the email wasn't altered in transit. It uses public-key cryptography, with the public key published in your DNS records.

A DKIM record contains:

• Version: The DKIM version (typically v=DKIM1)
• Key type: The encryption algorithm (usually RSA)
• Public key: The encoded public key used for verification

DMARC (Domain-based Message Authentication)

DMARC builds on SPF and DKIM, enabling you to specify what actions should be taken when authentication fails. You can set policies ranging from monitoring-only (p=none) to quarantine or rejection.

A strong DMARC policy example:

v=DMARC1; p=reject; rua=mailto:[email protected]; pct=100

This tells recipient servers to reject emails that fail authentication and send aggregate reports to your monitoring address.

Modern DNS lookup tools provide sophisticated capabilities beyond basic record queries:

DNSSEC Validation

DNS Security Extensions (DNSSEC) cryptographically authenticate DNS responses to prevent spoofing and cache poisoning attacks. When enabled, DNSSEC ensures the DNS records you receive are genuinely from the authoritative nameserver and haven't been tampered with during transmission.

DNSSEC uses a chain of trust:

• DNSKEY records: Public keys for zone signing
• RRSIG records: Digital signatures for record sets
• DS records: Delegation signer records linking to parent zones

SSL/TLS Certificate Discovery

Advanced DNS tools can scan multiple subdomains (often 20+) to discover SSL/TLS certificates and identify expiration issues before they cause service disruptions. This is crucial for:

• Preventing unexpected certificate expiration
• Identifying orphaned subdomains with expired certificates
• Maintaining security compliance across your infrastructure
• Avoiding browser warnings that erode user trust

Global DNS Propagation Analysis

When you update DNS records, changes don't take effect instantly worldwide. Propagation analysis queries multiple DNS servers (typically 8+ major providers) across different geographic regions to verify your records have propagated correctly.

This helps you:

• Confirm DNS changes have taken effect globally
• Identify propagation delays in specific regions
• Troubleshoot inconsistent DNS behavior
• Plan maintenance windows based on actual propagation times

DNS lookup and email security checks are essential for various scenarios:

Troubleshooting Email Deliverability

When your emails aren't reaching recipients, DNS records are often the culprit. Check for:

• Missing or misconfigured SPF records causing soft bounces
• DKIM signatures failing due to incorrect DNS entries
• Overly restrictive DMARC policies blocking legitimate mail
• Exceeding the SPF 10-lookup limit (too many includes)

Security Auditing

Regular DNS audits help identify security gaps:

• Domain spoofing protection: Ensure email authentication is properly configured
• Subdomain takeover risks: Find orphaned DNS records pointing to decommissioned services
• Certificate management: Track SSL/TLS expiration across your entire infrastructure
• DNS hijacking detection: Verify records haven't been maliciously altered

Email Provider Migration

When migrating between email providers (e.g., from Gmail to Microsoft 365), DNS verification is critical:

1. Verify new provider's MX records are configured correctly
2. Update SPF records to authorize new mail servers
3. Configure DKIM for the new provider
4. Monitor DMARC reports during the transition period
5. Confirm global DNS propagation before decommissioning old services

Reputation Monitoring

Proactive DNS monitoring helps maintain your domain reputation:

• Track SPF alignment to prevent unauthorized use of your domain
• Monitor DMARC reports to identify spoofing attempts
• Verify your domain isn't listed on DNS-based blocklists (DNSBLs)
• Ensure proper reverse DNS (PTR records) for your mail servers