DNS record lookup
Look up the records a domain publishes: addresses, mail servers, TXT records, name servers, certificate rules and more.
A domain, an email address or a URL. Lookups go from your browser to Cloudflare's public DNS (1.1.1.1); nothing is sent to simmail.
What DNS records do
DNS turns names into the information computers need to reach a service. Each name can carry several kinds of record, and each kind answers a different question:
- A and AAAA: the IPv4 and IPv6 addresses of a host.
- MX: which servers accept email for the domain, and in what order.
- TXT: free text. Email authentication lives here: SPF at the domain, DKIM keys under
_domainkey, DMARC at_dmarc, plus verification strings from services you use. - NS: the name servers that are authoritative for the zone.
- CNAME: an alias that points one name at another.
- CAA: which certificate authorities may issue TLS certificates for the domain (RFC 8659).
- SOA: the zone's start of authority: primary server, administrator mailbox, serial number and timers.
Why it matters for email
Almost every email problem that is not about content is a DNS problem. A sending service asks you to add TXT and CNAME records; a missing character or a record on the wrong name leaves SPF or DKIM failing, and since February 2024 Gmail and Yahoo require every sender to authenticate. Looking at what is really published, rather than what the DNS host's control panel shows, is the quickest way to find the mistake.
Common mistakes
- The domain added twice. Many DNS panels append your domain automatically, so entering
_dmarc.example.comcreates_dmarc.example.com.example.com. Look the record up by its full name here to be sure. - TXT records split or quoted wrongly. Long records must be split into strings of up to 255 characters; stray quotes become part of the value.
- Changes "not working" yet. Resolvers keep the old answer until its TTL runs out. Lower the TTL a day before a planned change.
- A CNAME next to other records. RFC 1034 does not allow it, and resolvers behave unpredictably when it happens.
For a focused check of one record, use the MX lookup, the SPF checker or the DMARC checker, which also tell you what to fix.
Questions
Which DNS server answers these lookups?
Cloudflare's public resolver (1.1.1.1), asked over HTTPS straight from your browser. It returns what the domain's authoritative servers publish, cached for up to each record's TTL.
Why does a name show a CNAME and an A record?
A CNAME makes a name an alias of another. The resolver follows it and returns the target's records, so you see the alias and then the final addresses.
Why is there no CNAME at the root of my domain?
A CNAME cannot sit alongside other records, and the root of a zone always has SOA and NS records. Some DNS hosts offer "flattening" or ALIAS records that behave like a CNAME but publish A records instead.
What is the TTL?
Time to live: how many seconds resolvers may cache the answer. The number shown is what is left in Cloudflare's cache, so it counts down between lookups.
What does "NXDOMAIN" mean?
The name does not exist at all. "No records" means the name exists but has nothing of that type.
Your DNS is right. Now see how real people react to your email
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