SEO tools
DNS Checker: Look Up Every Record for a Domain
Queries the live DNS for the domain you enter and reports the records it publishes: the addresses it resolves to, where its mail goes, and whether the TXT records email authentication depends on are present.
What this DNS checker reports
These are read live rather than from a cache, so a record you just changed may still show its old value if resolvers between you and the authoritative server have not expired it yet.
- A and AAAA records — the IPv4 and IPv6 addresses the hostname resolves to.
- MX records — the mail servers responsible for the domain.
- SPF, as a TXT record — which servers are allowed to send mail as this domain.
- DMARC, as a TXT record on the _dmarc subdomain — what receivers should do with mail that fails authentication.
What DNS has to do with SEO
DNS is upstream of everything else. If a hostname does not resolve, no crawler reaches the site at all, and every other signal is irrelevant. That makes DNS the first thing to check when a site disappears entirely rather than merely slips in rankings.
It also decides which hostname is real. A missing record for the www or non-www variant is the most common cause of one version working and the other failing outright — which then shows up as a canonical or redirect problem when the actual fault is a missing record.
| Record | Answers | Common failure |
|---|---|---|
| A / AAAA | Which server serves this hostname | Only one of www / non-www is defined |
| MX | Where mail for this domain goes | Points at a host that no longer exists |
| TXT (SPF) | Who may send mail as this domain | Two SPF records, which invalidates both |
| TXT (DMARC) | What to do with failing mail | Absent, so nothing is enforced |
Reading the result
An empty result for a record type is not automatically a fault — plenty of domains legitimately publish no MX record because they send no mail. What matters is whether the records match what the domain is actually used for. For the meaning of each type see DNS record types explained , and for why a change has not appeared yet see DNS propagation .
A example.com 93.184.216.34
MX example.com 10 mail.example.com
TXT example.com v=spf1 include:_spf.example.net -all
TXT _dmarc.example.com v=DMARC1; p=quarantine; rua=mailto:dmarc@example.com
Read it in order: the A record makes the web host reachable;
the MX host must resolve too; SPF authorises senders; DMARC
tells receivers what to do when SPF or DKIM fails.Investigate one record without guessing
Use the nslookup and dig command guide to query one resolver and record type, and the DNS record types guide to decide whether the record is expected for the service you run.
- Why does this show an old record I already changed?
- Resolvers cache records for the length of their TTL. Until that expires, a lookup can legitimately return the previous value even though the authoritative server has the new one.
- Does a missing AAAA record hurt SEO?
- No. IPv6 is optional, and Googlebot reaches IPv4-only sites without difficulty. Publish AAAA when your hosting supports it, but its absence is not a defect.
What this tool does not do
A DNS lookup means several different jobs, and this one answers a specific slice of them. Being explicit is cheaper than a wrong result.
| You want | This tool | Use instead |
|---|---|---|
| A, AAAA, MX, SPF, DMARC for a domain | Yes | — |
| Reverse DNS for an IP | No | dig -x, or your host |
| Propagation across world resolvers | No — one resolver, one moment | A multi-resolver propagation tool |
| Who owns an IP address | No — domains only | A regional registry (RIPE, ARIN) |
| DNS leak on a VPN | No | A VPN leak test |
- Is this the same as nslookup or dig?
- Same source, narrower question. nslookup and dig let you ask for any record type from any resolver; this reports the records that decide whether a site resolves and whether its mail authenticates, with a note on what each one means.
- Why no NS or CNAME record?
- They rarely change the answer to "can this site be reached and can it send mail". A CNAME resolves to the same A record already shown, and a nameserver problem shows up as no A record at all.
Other tools
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Reads the canonical URL a page declares, then fetches that URL to confirm it resolves, is not redirected, and is not noindexed — the three ways a canonical silently becomes inert.
Parses the structured data on the page you enter, lists the schema.org types it finds, and flags blocks that fail to parse or are missing the properties their type requires.
Follows the URL you enter through every hop, reporting the status code at each step and the final destination — the detail a browser hides once the address bar settles.
Fetches the page you enter, takes a sample of the internal links it points at, and requests each one — reporting the status code that comes back instead of the colour of the link.
Checks every signal that decides whether a page is allowed into the index — the status code, robots.txt access, meta robots, the X-Robots-Tag header, and the canonical.
Queries the registry over RDAP — the structured successor to classic WHOIS — and reports when the domain was registered, how old it is now, who the registrar is, and when the registration lapses.
Enter a domain to find when it was registered, how old it is today, when it expires, and which registrar holds it. Domain age is context for a diagnosis, not a Google ranking factor.
Opens a TLS connection to the host you enter and reports the certificate it presents — the issuer, the validity window, the days remaining, and the negotiated protocol version.
Requests the URL you enter and reports what the server sends back in its headers — the security headers present, the caching policy, whether the response is compressed, and which HTTP version was negotiated.