You configure a domain's email and it doesn't arrive. You point a domain at a new server and the site keeps showing the old version. You add a subdomain and it doesn't resolve. In all three cases, the first diagnostic step is the same: look at what the domain's DNS actually says right now, not what you think you configured.
What DNS is, in short
DNS is the system that translates domain names (example.com) into the information servers need to act: which IP it points to, which server handles its email, which external services are authorized. That information is organized into records, each with a different type and purpose.
The most important record types
- A: points the domain to an IPv4 address. The most basic record: it defines where the site lives.
- AAAA: same as A, but for IPv6.
- MX (Mail Exchange): indicates which server handles that domain's email. If it's misconfigured or missing, email simply doesn't arrive.
- TXT: a free-text record, used mainly for domain ownership verification and to configure SPF (which servers are allowed to send email on your behalf), key for email security.
- NS (Name Server): indicates which DNS servers are the authority for that domain. If these are wrong, no other record resolves correctly.
- CNAME: makes a subdomain point to another domain name instead of directly to an IP. Widely used for third-party services (
blog.example.compointing to the blog provider). - SOA (Start of Authority): contains administrative data for the DNS zone, such as the primary DNS server and refresh time.
How to look up a domain's DNS records
- Type the domain you want to look up.
- Choose the record type (A, MX, TXT, NS, CNAME, SOA...) or query all of them.
- Review the result in real time.
You can do it free with the DNS Lookup on this site, which queries records via Cloudflare in real time.
Why "real time" matters: DNS propagation
When you change a DNS record, that change doesn't apply instantly across the whole internet. DNS servers worldwide cache a copy for a period (the TTL, time to live, set in the record itself), so a change can take anywhere from minutes to 48 hours to show up depending on where it's queried. Querying DNS directly (instead of trusting what you see in your own browser, which may have a cache) gives you the actual state at that moment.
Common diagnostics with this tool
- Email isn't arriving: check the MX record; if it's empty or points to the wrong server, that's the problem.
- The site keeps showing old content after a hosting change: check the A record; if it still points to the previous IP, the change hasn't propagated or wasn't saved correctly.
- A subdomain isn't working: check whether the corresponding CNAME or A record exists.
- Verifying email security configuration: the TXT record with SPF is the first step before checking DKIM and DMARC in more detail.
Frequently asked questions
Why do I see a different result than my domain provider shows? It could be propagation in progress, or that you're querying a DNS server with a stale cache; a direct query like this usually shows the most recent state.
Do I need to own the domain to look it up? No, DNS records are public by design; anyone can query them.
What do I do if the NS is wrong? Fix it in your domain registrar's panel; until it points to the correct DNS servers, no other record will resolve properly.
How long does a DNS change take to apply? It depends on the configured TTL, usually between minutes and a few hours, though in extreme cases it can take up to 48 hours.
Look up any domain's DNS records in real time for free with the DNS Lookup, via Cloudflare and with nothing to install.