DNS Lookup - Check A, MX, TXT and NS Records Online

DNS Lookup - Check A, MX, TXT and NS Records Online

What Is a DNS Lookup?

DNS is the system that translates a domain name into the IP address a browser can actually connect to. When you type a domain, your device asks a resolver; the resolver asks the domain's nameservers, and those nameservers return a set of records. A DNS lookup tool performs that query on demand and shows you the raw answer.

This matters because DNS sits underneath almost every connection problem. If a site will not load, the cause is frequently a missing record, a stale cached entry, or nameservers that were never updated after a migration — not the web server at all. Running a lookup separates a DNS problem from a hosting problem before you start troubleshooting the wrong layer. If the records look correct here but the site still fails to respond, the next step is to check whether the website is up or down from an external network.

How to Use This Tool?

1. Enter the domain name without http:// or https:// — for example example.com
2. Select the record type you want, or query all common types at once
3. Review the returned records, along with their values and TTL

No account or installation is required. The lookup runs against public nameservers, so the result reflects what the rest of the internet sees rather than what your own device has cached.

Understanding the Results

A and AAAA records point the domain to an IP address — IPv4 and IPv6 respectively. If the A record is missing or points to an old server, the domain will not resolve correctly no matter how well the hosting is configured.

CNAME records alias one hostname to another. These are common for subdomains like www or for third-party services. A CNAME cannot coexist with other records at the same name, which is a frequent source of configuration errors.

MX records direct email to the correct mail servers, with a priority number where lower values are tried first. If email is bouncing, the MX record is the first place to look.

NS records name the authoritative nameservers for the domain. After transferring a domain or changing hosts, these must update and until they do, the old provider still controls where traffic goes.

TXT records hold arbitrary text, most often SPF, DKIM, and DMARC entries for email authentication, or verification strings for services like Google Search Console.

TTL is the number of seconds a resolver is permitted to cache a record. A high TTL means changes take longer to propagate. Lowering TTL before a planned migration is a standard practice worth remembering.

What the Error Codes Mean

If a lookup failed before you arrived here, the code tells you which part of the chain gave up:

• NXDOMAIN — The nameserver was reached and said the name does not exist
• SERVFAIL — The lookup could not be completed, often due to DNSSEC or an unreachable nameserver
• NOERROR with no records — The name exists, but has no record of the type requested
• REFUSED — The server declined to answer, usually because it is not authoritative
• DNS_PROBE_FINISHED_NXDOMAIN — Chrome's wrapper around NXDOMAIN
• ERR_NAME_NOT_RESOLVED — Chrome's general resolution failure, often a resolver problem rather than the domain
• DNS_PROBE_FINISHED_BAD_CONFIG — Your own DNS configuration is broken, not the domain's

The distinction that matters most is between the first two. NXDOMAIN is an answer — something with authority said no, so the fault is in the records. SERVFAIL is a failure — nothing usable came back, so the fault is in the delegation, the nameservers, or DNSSEC. They send you to opposite ends of the system.

Two of these are local conditions rather than server problems: ERR_NAME_NOT_RESOLVED and DNS_PROBE_FINISHED_BAD_CONFIG. If either appears for every site rather than one, nothing on the server side will fix it. 

Our guide to DNS errors covers each code in detail, including the cases where a domain resolves perfectly, and the page still will not load.

When Is This Tool Useful?

• Confirming that a DNS change has propagated to public resolvers after a migration
• Diagnosing email delivery failures by verifying MX, SPF, and DKIM records
• Checking which nameservers a domain currently uses before or after a transfer
• Verifying that a subdomain points where you expect it to
• Confirming a domain resolves correctly before troubleshooting SSL — if DNS is fine but the connection is still refused, validate the SSL certificate next
• Checking the records behind a domain before pointing your own services at it

What This Tool Does Not Do

A DNS lookup shows the records as returned at the moment you run it, from this server's vantage point. DNS propagation is not instant or uniform: a record you just changed may already be visible here while a resolver in another country still serves the old value for hours. This tool queries a single resolver, so it is not a substitute for a multi-location propagation checker.

It also reports what the records say, not whether the destination works. A perfectly valid A record can point to a server that is switched off. Confirming the records is step one; confirming the server responds is a separate check.

Frequently Asked Questions

How do I check which nameservers a domain is using?

 Enter the domain above and query the NS records. Those name the authoritative nameservers currently responsible for the domain. After a transfer or host change, these must update until they do, the previous provider still controls where the domain's traffic goes.

How do I check a domain's MX records?

 Enter the domain and select MX, or query all record types at once. The results list each mail server with its priority number, where lower values are tried first. If email is bouncing or silently failing, this is the first place to look before checking anything else.

How can I check if my DNS has propagated?

 Run the lookup and compare the returned values against what you configured. This queries a public resolver rather than your own device, so the result reflects what the wider internet sees. Propagation is not uniform, though — a record visible here may still be cached elsewhere.

How do I find out what IP address a domain points to?

 Query the A record for IPv4, or AAAA for IPv6. That is the address a browser actually connects to. If the A record is missing or still points to a previous server, the domain will not resolve correctly no matter how the hosting is configured.

Why does my DNS change not show up yet?

 Resolvers cache records for the duration of the TTL. If the previous TTL was set to 24 hours, resolvers that cached the old value before your change will keep serving it until that period expires. Lowering the TTL in advance of a change is the usual way to avoid this.

What is the difference between an A record and a CNAME?

 An A record points directly to an IP address. A CNAME points to another hostname, which must itself resolve to an IP. Use an A record for a root domain and a CNAME for subdomains that should follow another host.

Why is my email not arriving even though the domain works?

 Web traffic and email are controlled by different records. The A record can be perfect while the MX record is missing or pointing at a decommissioned mail server. Check the MX entries specifically.

Do I need to include www in the domain?

 No. Enter the root domain to see its records. Query the www subdomain separately if you want to confirm how it is configured, since it is often a CNAME rather than an A record.