Compare answers, not guesses
Enter a domain without a URL scheme, path or port. Internationalized domain names are converted to their ASCII DNS form before querying. Select the record type you need. Both resolvers receive the same name and type, and the report shows their answers separately instead of merging away useful differences.
The first report is produced as the page loads, using the host name this site is served from, so there is something real to read before you type. Every answer carries its own timestamp and the name of the resolver that produced it.
A records hold IPv4 addresses; AAAA records hold IPv6 addresses. MX records describe mail routing, TXT records often contain verification or email-policy text, and NS records identify name servers. SOA records contain zone administration information. CAA concerns certificate-authority authorization. DS and DNSKEY help inspect DNSSEC. PTR queries require a reverse-DNS name such as 1.1.1.1.in-addr.arpa, not a plain IP address — the reverse DNS lookup page builds that name for you.
Understand the status
NOERROR means the DNS query was processed successfully; it does not guarantee that an answer of the requested type exists. A successful empty answer can be normal when a domain has no AAAA record, for example. NXDOMAIN says the queried name does not exist according to that resolver. SERVFAIL can arise from upstream failures or validation problems. A network timeout is displayed as a provider error, not converted into NXDOMAIN.
The authority section is shown when returned. It can help explain negative responses or referrals. The table preserves answer names, numeric record types, TTL values and record data, so the JSON export can be compared with another diagnostic tool. What each of those record types is for, and which ones you can safely ignore, is collected in the DNS record types reference.
Why answers can differ
Resolvers cache independently. During a change, one may still hold an older valid answer. CDNs and managed DNS can also intentionally return different address sets based on routing policies. Therefore a difference is a prompt to investigate, not automatic proof of a broken zone.
The comparison ignores record ordering and TTL differences when deciding whether answer sets agree. TTL naturally changes as caches age. Record content and response status still matter. A response time measures the server’s request to the resolver; it is not the browser’s latency to the final website.
A second resolver will not always agree even when nothing is being changed. Large networks answer from many locations, and a managed service may deliberately return a different address set depending on which facility is asked, so a difference between two resolvers can describe routing policy rather than a mistake. What a difference rules out is nothing at all, and what it establishes is that the question is worth asking again from a different vantage point.
The export is the part that makes this page useful for a change window rather than for a single moment. Download the report before the change, make the change, download it again, and compare the two: the answer sets and the status codes are recorded with their timestamps, so the difference between the two files is the change that actually happened on the resolver side, as opposed to the change that was intended.
What this is not measuring
These are two public resolvers queried from the service’s execution location. They are not probes physically deployed in dozens of countries. The tool does not claim to establish worldwide propagation, test every authoritative server or verify that a website’s HTTP service is healthy. DNSSEC authenticated means the resolver set its AD flag; an unset flag alone does not prove a configuration error.
It also does not tell you how long a change will take to be seen everywhere — that depends on the TTL that was on the record before you changed it, which is what the DNS TTL calculator works out from two numbers you supply.
Export a report before and after a change if you need a comparison. Use IP Check to inspect an address returned by DNS. See the network guide for a practical investigation order. The query formats are documented by Cloudflare and Google.