Knowledgebase

This article explains what DNS lookup tools are, when to use them and which tools are commonly recommended. It also includes examples of the main DNS record types customers may need to check.

DNS is the system that translates domain names into the records used by websites, email services and other internet services. A DNS lookup tool queries public DNS and shows the records currently visible on the internet for a domain or hostname.

These tools let you verify live DNS results independently of your hosting control panel. You may have already updated a record in your DNS manager, but a lookup tool can help confirm whether the change is publicly visible.

Note: DNS lookup tools show the public DNS records that resolvers can see. They do not always confirm what is saved inside your DNS hosting platform if the change has not propagated or if the zone was not saved correctly.

You may want to use a DNS lookup tool when:

* You have changed DNS records and want to confirm the live result.

* Your website is not loading and you need to check the A record or CNAME record.

* Your email is not sending or receiving and you need to inspect MX, SPF, DKIM or DMARC records.

* You are migrating hosting and need to confirm that a domain points to the correct server.

* You want to review name servers for a domain.

* You need to inspect TXT records for verification or email authentication.

* You want to check whether a mail server IP or domain appears on a blocklist.

We recommend using MXToolbox for DNS record lookups, as you can select specific records to check and perform blocklist or blacklist searches.

We recommend using http://whois.com for performing WHOIS lookups to identify public domain registration details.

When you are not using a web-based tool, DNS lookups are usually performed using PowerShell on Windows, Terminal on macOS or a Linux Bash shell.

Maps a domain or hostname to an IPv4 address. This is commonly used to point a website to its server.

Maps a domain or hostname to an IPv6 address.

Points one hostname to another hostname instead of directly to an IP address. This is often used for subdomains such as www.

Specifies which mail server receives email for the domain. If email is not arriving, this is one of the first records to check.

Stores text-based DNS data. TXT records are commonly used for domain verification, SPF policies and other service validations.

Shows which name servers are authoritative for the domain. This helps confirm where DNS is hosted.

SPF, DKIM and DMARC are commonly used for email authentication. SPF defines permitted sending servers, DKIM helps receiving servers verify that an email was authorised by the domain owner, and DMARC tells receiving servers how to handle messages that fail authentication checks.

1. Open MXToolbox in your web browser.

2. Enter your domain name, hostname or mail server name in the search field.

3. Select the lookup type you want to run, such as MX Lookup, DNS Lookup, SPF Record Lookup, DKIM Lookup, DMARC Lookup or Blacklist Check.

4. Run the search.

5. Review the returned records and diagnostic results.

6. If required, compare the live result with the settings you expected to see in your DNS hosting platform.

[Screenshot: MXToolbox lookup search field and record type selector]

For example:

* Use an MX lookup to see which mail servers handle email for your domain.

* Use an SPF or TXT lookup to confirm whether an email sending policy is published.

* Use a DKIM lookup to verify that the selector record exists.

* Use a DMARC lookup to confirm your DMARC policy.

* Use a blacklist check if your domain or mail server is experiencing email delivery or reputation issues.

1. Open http://whois.com.

2. Enter the domain name you want to check.

3. Run the search.

4. Review the public WHOIS information shown for the domain.

A WHOIS lookup may help you identify domain registrar information, registration status or name server details, depending on the domain extension and the level of privacy protection applied.

[Screenshot: whois.com domain WHOIS lookup page]

* DNS changes are not always visible immediately. Some updates take time to propagate across DNS resolvers.

* Local device or browser caching can sometimes make a recent DNS change appear inconsistent.

* If your domain uses third-party DNS hosting, the live records shown by a lookup tool may reflect that provider rather than your web hosting service.

* Email-related DNS issues often involve more than one record. MX, SPF, DKIM and DMARC may all need to be checked together.

* A correct DNS record can still fail to work if it was entered with the wrong hostname, priority, formatting or destination value.

Recommendation: Do not confuse domain registration details, name server delegation and DNS zone records. These are related, but they are not the same thing and may be managed in different platforms.

This usually means the new record has not propagated, the change was not saved correctly, or the domain is using different name servers than expected. Confirm the domain's active name servers first, then recheck the record after allowing time for propagation.

Check the A record, AAAA record or CNAME record for the domain and any relevant subdomain such as www. Also check whether your device or internet provider is still using cached DNS results.

Website DNS and email DNS often rely on different records. Check the MX record first, then review SPF, DKIM and DMARC if sending or authentication problems are involved.

This may indicate that delegation at the registrar has not been updated, or that you are editing DNS in the wrong platform. The authoritative name servers determine which DNS zone is live for the domain.

MXToolbox is useful for email troubleshooting because it can check MX, SPF, DKIM, DMARC and blocklist status from one interface.

A DNS lookup tool can show what a particular resolver sees, but propagation can vary by location, resolver cache and record TTL. Results may not be identical everywhere immediately after a change.

A DNS lookup shows active DNS records for a domain or hostname. A WHOIS lookup shows public registration information and related domain details where available.

• What is DNS? (DNS)

• Nameservers (DNS)

• DNS Propagation (DNS)

• Zone Files (DNS)

If you require further assistance, please contact Apexhost Support at support@apexhost.com.au.