Nameserver Checker

Verify nameserver configuration and delegation for any domain. Free NS record checker with response times, consistency validation, and authoritative server analysis.

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APIPOST /api/v1/dns/nameservers
4.8(16 votes)
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Try also: DNS Lookup
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Key Features

100% Free

No registration required, unlimited checks

Instant Results

Real-time analysis with detailed output

REST API Access

Integrate into your workflow via API

Accurate Data

Live queries to authoritative sources

What is Nameserver Checker?

The nameserver checker performs a comprehensive verification of NS record configuration and DNS delegation for any domain. It queries the root DNS servers to find the delegated nameservers, then contacts each one directly to measure response times, verify they are reachable, and check that all nameservers return consistent DNS records. Properly configured nameservers are the foundation of your domain's DNS infrastructure — if nameservers are misconfigured, unreachable, or inconsistent, your website won't load, email won't be delivered, and all services tied to the domain will fail.

This free NS checker tool is essential after switching DNS providers (to verify delegation propagated correctly), when troubleshooting intermittent DNS resolution failures, for routine audits of your domain's DNS health, and when setting up new domains to confirm nameserver assignments are active. The tool checks both NS records at the parent zone (registry delegation) and the actual nameserver responses to identify delegation mismatches, lame delegations, and inconsistent zone data.

How to Use

  1. 1Enter the domain name to check its nameservers (e.g., example.com)
  2. 2Click 'Run Check' to query NS records from both the parent zone and the nameservers themselves
  3. 3Review the list of assigned nameservers with their IP addresses and response times
  4. 4Check for consistency — all nameservers should return the same set of records for the domain
  5. 5Verify response times are acceptable — high latency nameservers can slow down DNS resolution for your visitors

Who Uses This

System Administrators

Monitor and troubleshoot infrastructure

Developers

Debug network issues and integrate via API

SEO Specialists

Verify domain configuration and performance

Security Analysts

Audit and assess network security

Frequently Asked Questions

What are nameservers and why do they matter?
Nameservers are specialized DNS servers that store and serve the DNS records for your domain — A records (website IP), MX records (email servers), TXT records (SPF, DKIM), and more. When someone types your domain name in a browser, the DNS system contacts your nameservers to find the correct IP address. If nameservers are down or misconfigured, your entire online presence — website, email, and all connected services — becomes unreachable. Think of nameservers as the authoritative source of truth for where your domain's traffic should go.
How do I check my domain's nameservers?
Enter your domain name in the NS Checker tool and run the check. The tool queries the parent zone (e.g., .com registry) to find which nameservers are delegated for your domain, then contacts each nameserver directly to verify it's responding correctly. You'll see nameserver hostnames, their IP addresses, response times, and whether they return consistent data. You can also check your nameservers through your domain registrar's dashboard, but this tool provides an independent external verification.
How many nameservers should a domain have?
A domain should have at least two nameservers for redundancy — this is actually a requirement in the DNS specification (RFC 1034). If one nameserver goes down, the other continues serving DNS queries. Most DNS providers assign two to four nameservers, often geographically distributed across different data centers or even different networks. Having nameservers on different IP subnets and in different locations improves resilience against hardware failures, network outages, and DDoS attacks.
What is a lame delegation and how do I fix it?
A lame delegation occurs when the parent zone (registry) delegates DNS authority to a nameserver that doesn't actually have the zone data for your domain. For example, if your registrar points to ns1.olddns.com but that server no longer has your DNS records, it's a lame delegation. This causes DNS resolution failures for some or all queries. To fix it, update your nameserver records at your registrar to point to the correct, active nameservers that actually host your DNS zone. The NS Checker tool helps detect this by comparing delegation records with actual nameserver responses.
Why should all nameservers return the same records?
DNS resolvers randomly choose which nameserver to query, so all nameservers must return identical records. If nameserver A returns a different IP address than nameserver B for the same domain, visitors will be randomly directed to different servers depending on which nameserver their resolver contacted. This causes intermittent issues that are extremely difficult to diagnose — your site might work for some users but not others, or work sometimes but fail other times. The NS Checker tool verifies consistency across all assigned nameservers to catch this problem.

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API Endpoint

POST /api/v1/dns/nameservers
View Documentation