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A DNS lookup shows the records that tell the internet where a domain’s website, email and other services live. The free DNS Lookup tool queries public DNS over HTTPS and lists the A, AAAA, MX, TXT, CNAME and NS records for the domain you enter, so you can verify them in seconds.
Mozilla’s glossary explains that DNS (Domain Name System) is a hierarchical and decentralised naming system whose primary function is to translate human-friendly domain names into numeric IP addresses; see Mozilla’s glossary for the definition.
How to use the DNS Lookup
- Enter the domain name, such as example.com, without https:// or a path.
- Run the lookup. Your browser asks a public DNS over HTTPS service for the records.
- Read each record type in turn, starting with A or AAAA for the website and MX for email.
- Compare what you see with what you expect from your host or email provider.
- If you change a record, check again after a while, because DNS changes do not always appear everywhere at once.
How to read the results
| Record | What it does | What to look for |
|---|---|---|
| A | Points the domain to an IPv4 address | The address of your current host |
| AAAA | Points the domain to an IPv6 address | Optional, but it must be correct if present |
| CNAME | Makes one name an alias of another | Aliases such as www pointing to the right target |
| MX | Says which servers receive email | Your email provider’s servers |
| TXT | Holds text such as verification codes and email authentication | Entries for SPF, DMARC and site verification |
| NS | Lists the name servers that control the domain’s DNS | The provider where you actually manage DNS |
What to fix
- Website down after a move. If the A record still points at an old host, visitors reach the wrong server. Update it to the new address.
- Email not arriving. Missing or wrong MX records are a frequent cause. Compare them with your provider’s instructions.
- Email landing in spam. Look in the TXT records for email authentication entries. If they are absent, ask your email provider what to add.
- Old IPv6 address. A forgotten AAAA record can send some visitors to a server you no longer use.
- Wrong name servers. If NS records point to a provider you stopped using, edits made elsewhere will have no effect.
Why DNS matters for SEO
DNS is invisible when it works and disastrous when it does not. If a domain does not resolve, neither visitors nor search engine crawlers can reach the site. After a migration, incorrect records can leave a site unreachable for a while, and unreachable pages cannot be crawled or indexed. Email records affect trust in a different way: a business whose messages go to spam loses leads. A lookup is a sensible first step whenever you change hosts, add a new service or see unexplained downtime. Check the HTTPS side at the same time with the SSL Certificate Checker.
Worked example (illustrative)
Imagine a clinic that moves its website to a new host on Friday. On Monday, staff say the site shows an old version and email feels slow. A lookup reveals the A record still shows the old host while the new host expects a different address. The fix is a single edit at the DNS provider, followed by another lookup to confirm. The same lookup also shows MX records that match the email provider, which rules out a second cause quickly.
Limits to keep in mind
The tool shows what public DNS returns when the request is made, not what your provider’s dashboard says you intended. Caching means different resolvers can briefly show different answers after a change. It lists records; it does not edit them, and it does not judge whether your configuration is right for your setup. Some record types, such as email authentication entries held under special names, may need a different query than the plain domain. There is a fair-use limit on repeated checks.
Questions about the DNS Lookup
Why do my DNS changes not show up straight away?
DNS answers are cached by resolvers, so a change can take time to spread. Check again later rather than changing the record repeatedly.
What is the difference between an A record and a CNAME?
An A record points a name directly to an IPv4 address. A CNAME makes one name an alias of another name, which then resolves to its own address.
Which record should I check if email stops working?
Start with the MX records, then look at the TXT records for email authentication entries. Compare both with what your email provider tells you to use.
DNS mistakes quietly break websites and email, and they are easy to miss without a quick check. Browse all the free SEO tools, see the full free domain and website lookup tools collection, or read about my technical SEO services. If you would like a person to look at your site, ask for a free audit.