A difference is a clue
Recursive resolvers cache DNS answers. During a record change, one resolver may still return a cached answer while another has fetched a newer value. Content distribution and resolver policy can also affect answers.
Compare like with like
Use the same domain and record type for each resolver. An A record is an IPv4 address; an AAAA record is an IPv6 address. Compare record sets rather than assuming that the order of addresses matters. Check whether a response was unavailable before interpreting a missing value.
Do not call it global propagation
Comparing Cloudflare, Google and Quad9 answers is resolver comparison. It does not show that a change is visible in every country. If a record was recently changed, verify the intended authoritative configuration and repeat the comparison after relevant cache lifetimes have elapsed.
Example
Illustrative A-record comparison Resolver A: 192.0.2.10 Resolver B: 192.0.2.20 These documentation addresses represent differing answers, not live hosts.
What to check next
- Choose A, AAAA, MX or another supported record type.
- Run DNS Resolver Comparison and separate unavailable responses from differing answers.
- Check the intended record with the DNS administrator. Record when it changed and compare again after caching can expire.