Free DNS Checker
Validate Name Server Health & Delegation
Check any domain's name server health for delegation issues, SOA mismatches, and slow responses.
Run a live check to identify DNS configuration issues that could affect your website or email.
About Free DNS Checker by DMARKOFF
Our Free DNS Checker verifies that a domain's name servers are correctly delegated, consistent, and responding reliably.
DNS misconfigurations are a common cause of website and email delivery problems. They can also weaken the foundation that email authentication relies on.
Detecting delegation or SOA issues early helps keep your DNS reliable and prevents problems that can affect website availability and email delivery.
What Is a DNS Health Check?
The Domain Name System (DNS) is the infrastructure that allows websites and email services to find your domain. A DNS health check verifies that your name servers are correctly delegated, consistent, and responding to queries.
Every domain should have at least two authoritative name servers, and the delegation in the parent DNS zone must match the name servers serving your DNS zone. If these don't match, or if a name server is slow or unreachable, DNS resolution can fail or become unreliable, affecting both website access and email systems that rely on DNS records such as MX, SPF, DKIM, and DMARC.
What the DNS Checker Detects
✓ Confirms your domain exists and publishes NS records
✓ Confirms each name server resolves to a valid IP address
✓ Confirms all name servers are responding to queries
✓ Verifies the primary name server is correctly delegated at the parent zone
✓ Confirms SOA serial numbers match across all name servers
✓ Confirms your domain has at least two name servers for redundancy
Why Choose Free DNS Checker
Free to use — no signup required to run your domain DNS health check.
Instant results — verify your DNS configuration in seconds.
Session history — compare DNS checks across multiple domains during your current session.
FAQ
Name server delegation is the process of linking a domain to its authoritative name servers through the parent DNS zone. If the delegated name servers don't match those serving the DNS zone, resolvers may receive inconsistent or outdated DNS data.
The SOA (Start of Authority) serial number tracks the version of a domain's DNS zone. If name servers report different serial numbers, it usually means a recent DNS change hasn't propagated to all servers yet, which can cause inconsistent answers depending on which server is queried.
Having at least two name servers provides redundancy. If one becomes unavailable, the other can continue serving DNS requests. Most registrars and DNS providers recommend or require at least two authoritative name servers.
DNS resolvers retry another available name server if one doesn't respond, but this adds latency. If too many name servers are unavailable, the domain may become unreachable for some users.
A Free DNS Checker by DMARKOFF verifies that your domain's name servers are correctly configured and responding consistently. It can quickly identify delegation issues, unreachable name servers, or SOA mismatches that may affect website availability or email delivery.
Check after changing your DNS provider, registrar, or name servers, and periodically afterward to catch propagation issues or configuration problems before they affect your services.