DNS Resolver Comparison
Enter a hostname and pick a record type. The same query is sent to each configured public resolver, and their answers are shown side by side.
- DNS
- Live check
- Free, no sign-up
- Results are not published
Run DNS Resolver Comparison
At a glance
- What it checks
- Ask several public recursive resolvers the same DNS question and see whether their cached answers agree.
- Data source
- The same query sent to each enabled public resolver.
- Freshness
- Live check; results are cached for up to 1 minute
- Limits
- Large resolvers are anycast networks, so this compares operators, not every location in the world. Methodology
- Cost
- Free, no account needed
Understanding the result
What this tool compares
The tool sends one query per resolver over DNS-over-HTTPS, by default to Cloudflare (1.1.1.1) and Google Public DNS (8.8.8.8), and lists each resolver's response code, record values, lowest TTL and DNSSEC authentication flag. Supported types are A, AAAA, CNAME, MX, NS, TXT, CAA and SOA.
Values are sorted before comparison, so two resolvers returning the same addresses in a different order are treated as agreeing.
What this tool is not
This is not a worldwide DNS propagation test. Both default resolvers are large anycast services, and each query reaches whichever of their sites is closest to DomainDNSCheck's server, not a set of locations around the globe. The comparison shows the state of those resolvers' caches, which is a practical indicator of whether a change has been picked up, but it does not tell you what an ISP resolver in a particular country is returning.
It also helps to know that "propagation" is a slightly misleading term. DNS changes are not pushed outward; each resolver simply keeps an old answer until its TTL runs out and then asks again. How DNS works explains caching in more detail.
Reading the result
- PASS: all resolvers that answered returned the same set of values.
- WARNING: at least two resolvers returned different values. This is normal for a while after a change, and also for services that return different addresses on purpose, such as CDNs and load balancers.
- UNKNOWN: fewer than two resolvers answered, so there is nothing to compare.
Look at the TTL column when answers differ. A resolver still serving the old value shows how many seconds remain before it will ask again. If the TTLs are long and you need the change live sooner, some resolvers offer a public cache-purge page.
When differences point to a real problem
If answers still disagree well after the old TTL has expired, the cause is usually at the source rather than in a cache: nameservers holding different zone versions, a half-finished migration between DNS providers, or a broken DNSSEC chain that makes one validating resolver return SERVFAIL. Check the delegation with the Nameserver Checker and the signature chain with the DNSSEC Checker. For a full record listing from a single resolver, use the DNS Lookup.
Frequently asked questions
Why not test from dozens of countries?
Doing that honestly requires servers or probes in each location. Tools that show world maps often query public resolvers that are themselves anycast, which says little about geography. This tool tells you exactly which resolvers were asked.
Both resolvers agree, but my computer shows the old value. Why?
Your device, browser or ISP resolver has its own cache. Flushing the local DNS cache or waiting for the old TTL to expire usually resolves it.
Why are the TTLs different between resolvers?
Each resolver counts down from the moment it cached the record. A resolver that fetched the record recently shows a TTL close to the zone's configured value, while one that cached it earlier shows less time remaining.