DNS Lookup: How to Check DNS Records Online and Troubleshoot Domain Problems

A DNS lookup allows you to view the Domain Name System records published for a domain or hostname. It can help you confirm where a website is hosted, which servers receive email, which nameservers control the domain, and whether verification or security records have been published correctly.

Website owners, system administrators, developers, email administrators, and technical support teams frequently use online DNS lookup tools to diagnose website outages, email delivery failures, domain configuration mistakes, and DNS propagation delays.

Check DNS records online with the DNSCheckers.com DNS Lookup Tool.

What Is a DNS Lookup?

A DNS lookup is a query that requests information stored in the DNS. The requested information is returned as one or more DNS resource records.

For example, when a user opens a website, DNS helps translate the domain name into an IP address that the user's device can connect to.

A DNS lookup can answer questions such as:

• What IP address does this domain point to?
• Which mail server receives email for the domain?
• Which DNS provider manages the domain?
• Does the domain have an SPF, DKIM, or DMARC record?
• Does a subdomain point to another hostname?
• Has a DNS change propagated correctly?
• Is DNSSEC information published?

Which DNS Records Can You Check?

A complete DNS record lookup may include the following record types.

A Record

An A record maps a domain or hostname to an IPv4 address.

example.com → 192.0.2.10

Check the A record after changing hosting providers, moving a website, or updating a server's public IPv4 address.

AAAA Record

An AAAA record maps a hostname to an IPv6 address.

An obsolete AAAA record can cause some users to reach the wrong server even when the IPv4 A record is correct.

CNAME Record

A CNAME record makes one hostname an alias of another hostname.

www.example.com → example.com

CNAME records are commonly used for hosted applications, content delivery networks, cloud services, and subdomains.

MX Record

MX records identify the mail servers responsible for receiving email for a domain.

An MX lookup is useful after migrating to Microsoft 365, Google Workspace, or another email provider.

TXT Record

TXT records contain text-based information used for email authentication, domain verification, and service configuration.

Common TXT-based records include:

• SPF
• DKIM
• DMARC
• Google verification
• Microsoft verification
• Third-party platform verification

NS Record

NS records identify the authoritative nameservers responsible for the domain's DNS zone.

If you edit DNS records at the wrong provider, the changes will not affect the live domain. An NS lookup helps identify the active DNS provider.

SOA Record

The Start of Authority record contains administrative and timing information about a DNS zone, including its primary nameserver and serial number.

PTR Record

A PTR record maps an IP address back to a hostname. This process is known as a reverse DNS lookup.

PTR records are especially relevant to mail servers, server logs, and network troubleshooting.

CAA Record

A CAA record specifies which certificate authorities are permitted to issue SSL or TLS certificates for a domain.

SRV Record

An SRV record publishes the hostname and port used by a specific service.

DNSKEY and DS Records

DNSKEY and DS records are used by DNSSEC to establish a chain of trust for signed DNS data.

How to Perform an Online DNS Lookup

1. Open the DNS lookup tool.
2. Enter the domain or full hostname.
3. Select the DNS record type.
4. Select ALL when you need a complete domain DNS check.
5. Run the lookup.
6. Compare the returned records with your intended configuration.

Always check the exact hostname involved in the problem.

For example:

example.com
www.example.com
mail.example.com
portal.example.com
selector1._domainkey.example.com
_dmarc.example.com

A lookup for example.com does not automatically check every subdomain.

DNS Lookup vs DNS Propagation Checker

A DNS lookup normally retrieves the current record from a selected resolver or authoritative source.

A DNS propagation checker compares the same record across multiple DNS servers and geographic locations.

Use a DNS lookup when you need to inspect the record itself. Use a global DNS propagation checker when you need to determine whether different resolvers are returning different values.

Check global DNS propagation with DNSCheckers.com.

How to Read DNS Lookup Results

The Expected Record Is Returned

The DNS record has been published, but you should still test the service that depends on it. Correct DNS does not guarantee that a website, mail server, firewall, or SSL certificate is configured correctly.

An Old Record Is Returned

The old record may still be cached, or you may have edited the wrong DNS zone.

No Record Is Returned

The record may not exist, the hostname may be incorrect, or an earlier negative response may still be cached.

SERVFAIL Is Returned

SERVFAIL can indicate a nameserver failure, DNSSEC validation problem, delegation error, or another DNS resolution problem.

NXDOMAIN Is Returned

NXDOMAIN means that the queried DNS name does not exist according to the resolver's response.

Common DNS Lookup Problems

• Checking the wrong hostname
• Selecting the wrong record type
• Editing an inactive DNS provider
• Leaving obsolete A or AAAA records active
• Publishing conflicting records
• Entering the full domain twice in a DNS control panel
• Using incorrect MX priorities
• Publishing multiple SPF records
• Using the wrong DKIM selector
• Breaking DNSSEC after changing nameservers

DNS Lookup Commands

Windows NSLookup

nslookup example.com
nslookup -type=MX example.com
nslookup -type=TXT example.com
nslookup -type=NS example.com

Linux and macOS Dig

dig example.com
dig A example.com
dig MX example.com
dig TXT example.com
dig NS example.com

An online DNS lookup is often easier when you need a quick result without using command-line tools.

DNS Troubleshooting Checklist

1. Confirm the exact domain or hostname.
2. Check the active NS records.
3. Query the required record type.
4. Check both A and AAAA records.
5. Compare authoritative and recursive results.
6. Review the TTL.
7. Check global DNS propagation.
8. Verify the destination server.
9. Inspect the SSL certificate.
10. Test website and email services separately.

Frequently Asked Questions

What does a DNS lookup show?

A DNS lookup can show IP addresses, mail servers, nameservers, aliases, TXT values, DNSSEC records, service records, and other information published in DNS.

Can I check all DNS records at once?

Yes. Select the ALL option in a full DNS lookup tool to retrieve the supported record types.

Why do two DNS lookup tools show different results?

The tools may query different recursive resolvers, use different caches, or query authoritative nameservers directly.

Does a DNS lookup change anything?

No. A lookup reads DNS information. It does not edit, delete, or publish records.

Conclusion

A DNS lookup is one of the most useful tools for diagnosing domain, website, email, and nameserver problems. Check the exact hostname, select the correct record type, and compare the result with the configuration required by your hosting or service provider.

Use the DNSCheckers.com DNS Lookup Tool to check A, AAAA, CNAME, MX, NS, PTR, SOA, TXT, CAA, DS, DNSKEY, and other supported DNS records.