DNS lookup across eight resolvers
The same question asked of eight public resolvers at once, so you can see where a change has propagated and where it has not.
How to read this
Why eight resolvers instead of one
A single lookup tells you what one resolver currently believes. That is rarely the question. After a change, the question is whether the world has caught up — and the world does not update at once. Each resolver caches an answer until its time-to-live expires, so for anywhere between minutes and a day, different people genuinely see different answers. Asking eight at the same moment turns an invisible problem into a visible one: if they disagree, the change is still in flight and you are not imagining it.
What each record type answers
A and AAAA give the IPv4 and IPv6 addresses a name points to. MX says which servers accept mail for the domain, in priority order. TXT holds the text records that SPF, DKIM and domain verification live in. NS names the authoritative servers. CNAME points one name at another. SOA carries the zone’s serial number and timers — a serial that has not changed means your edit never reached the zone. CAA restricts which certificate authorities may issue for the domain.
“No record” and “did not answer” are different
A resolver that returns nothing has told you something: this name exists, and there is no record of that type on it. A resolver that times out has told you nothing at all. This tool shows the two separately, because treating them the same is how people conclude a record is missing when the truth is that one resolver was slow. Each resolver gets two seconds and the page never waits for the slowest.
Doing this for a business rather than for yourself? Email Systems.
The other tools
Subnet Calculator
Ranges, masks and host counts for IPv4 and IPv6. Runs entirely in your browser — nothing you type is sent anywhere.
SSL Checker
Expiry, issuer, the names it covers, the chain, the protocol and the cipher — and plain sentences about anything that is wrong.
IP Lookup
What an address is, what it is for, which registry it was allocated to, and what it calls itself in reverse DNS.