DNS Health Checker

Run a full DNS diagnostic on a domain — nameserver delegation, glue records, SOA sanity, and MX configuration, each validated against RFC standards.

100% Free ~20 RFC Checks Queries Real Nameservers

Run DNS Health Check

This queries your domain's actual nameservers directly, not just a cached lookup — it can take a few seconds.

Querying nameservers directly — this takes a few seconds...

Secure by designYour domain is processed instantly over an encrypted connection and never stored on our servers.

Encrypted in transitSubmitted over HTTPS/TLS — nothing is sent in plain text.

Never storedThe domain you check and its results are not saved to any database or log.

No third-party sharingYour data is never shared with ads, trackers, or outside services.

Processed instantlyChecked on request and discarded immediately after the response.

About DNS Health Checker

What Is a DNS Health Checker?

A DNS health checker audits a domain's DNS configuration for common misconfigurations — missing records, conflicting entries, or setup errors — that can cause email delivery failures, site downtime, or inconsistent resolution.

How Our DNS Health Checker Works

Enter your domain, and the tool checks its full DNS setup against common best practices and known misconfiguration patterns, then reports any issues found.

How to Use the DNS Health Checker

Enter your domain
Click Check Health
Review any flagged issues
Fix problems through your DNS provider's control panel

Key Features

Comprehensive DNS audit — checks multiple record types at once
Clear issue flagging — know exactly what needs fixing

Who Uses This Tool

System administrators troubleshoot email deliverability or resolution issues. Site owners run a routine health check after DNS changes.

Frequently Asked Questions

How often should I check DNS health?
After any DNS change, and periodically as a routine check — misconfigurations can silently cause email delivery problems for a long time before being noticed.

Is this tool free?
Yes, checking DNS health is completely free.

Frequently Asked Questions

How is this different from a basic DNS lookup?

A basic lookup just shows you the records. This tool queries each of your nameservers directly, compares their answers, checks for RFC violations, and flags security issues like open recursion — the same kind of diagnostic used before a domain migration or when troubleshooting intermittent DNS problems.

What does "open recursion" mean and why is it bad?

An authoritative nameserver that also answers recursive queries for domains it doesn't host can be abused for DNS amplification attacks and cache poisoning. Authoritative nameservers should only answer for the zones they're responsible for.

What is a "lame" nameserver?

A lame nameserver is one that's listed as authoritative for a domain but doesn't actually respond authoritatively when queried — often caused by outdated NS records at the registrar or a misconfigured DNS server.

Why do my nameservers disagree on the SOA serial?

This usually means a recent zone change hasn't fully propagated to all your secondary nameservers yet. It typically resolves on its own within minutes to hours, depending on your SOA REFRESH interval.

Is a warning as serious as a failure?

No — warnings flag values that are outside typical recommended ranges but usually aren't breaking anything today. Failures (red) indicate something is actually misconfigured and likely causing real problems.

Does this tool modify anything on my domain?

No — it only sends read-only DNS queries. It can't and doesn't change any configuration on your domain or nameservers.