Which public DNS resolvers (Cloudflare, Google, OpenDNS, Quad9, etc.) return different results for duckduckgo.com and why?
Executive summary
Different public DNS resolvers — Cloudflare (1.1.1.1), Google (8.8.8.8), OpenDNS (208.67.222.222) and Quad9 (9.9.9.9) — usually resolve duckduckgo.com to the same set of authoritative IP addresses, but occasional differences appear because of caching, geo/load-balanced authoritative responses, and resolver-level blocking or filtering policies that some operators apply [1] [2] [3] [4]. Public resolver vendors also advertise different privacy, security and filtering features that can change whether a query succeeds, is rewritten, or is blocked — DuckDuckGo itself runs DNS for its VPN and maintains a scam-blocklist that alters responses when the VPN is active [5] [6].
1. How DNS normally yields the same answers — multiple authoritative IPs and CDN effects
DuckDuckGo’s domain is published with multiple A records and is reachable via a set of authoritative IP addresses, so a correct recursive resolver will typically return one or more of those addresses; community DNS lookups show duckduckgo.com resolving to addresses such as 176.34.131.233, 46.51.197.88, 176.34.135.167 and 46.51.197.89 depending on the authoritative reply and caching state [1]. Performance and geographic load balancing by authoritative systems and CDNs mean different resolvers or vantage points can legitimately receive different IPs or different ordering of the same IPs even when no resolver is “misbehaving” [2] [7].
2. When resolvers return different results: caching, time-to-live and propagation
Resolvers cache answers and obey TTLs; if one resolver has a fresh cached A record while another performs an uncached query to the authoritative servers, the two will commonly return different values or timings — a normal and expected difference that is visible in benchmarking and monitoring of public resolvers [2] [8]. Tools that compare resolvers’ performance and uptime show frequent per-location variance, which contributes to observed differences for a domain like duckduckgo.com [2] [7].
3. When resolvers intentionally alter or block responses: filtering and “family” policies
Some public resolvers implement content filtering or safe-search enforcement that can rewrite or block DNS answers; lists of resolvers and resolver configurations note explicit “family” or filtering modes that can block or force safe-search on search engines including DuckDuckGo in certain configurations [4]. User reports and support threads document cases where OpenDNS or specific resolver settings made DuckDuckGo appear unreachable or produced different behavior for that domain until the block was lifted or settings changed [3].
4. Security layers that change behavior: scam blocklists and provider DNS
DuckDuckGo’s own VPN ships configured to use DuckDuckGo DNS servers and applies a Scam Blocker that blocks >150,000 flagged domains at the DNS level, so using DuckDuckGo’s DNS can produce different outcomes than third-party resolvers when a domain is on that blocklist or when device-level blocking rules apply [5]. Conversely, security-focused resolvers like Quad9 also apply malware-blocking policies that will alter responses for flagged names, so behavior differences can stem from different blocklists rather than DNS protocol errors [4].
5. Privacy, commercial motives and hidden agendas that shape answers
Resolver operators market different tradeoffs — Google emphasizes scale and performance while acknowledging data collection policies, Cloudflare emphasizes privacy and speed, and family or “filtered” resolvers advertise child-safety or ad/malware blocking — these commercial or policy choices explain why one resolver might intentionally refuse, redirect, or filter a duckduckgo.com query under certain settings [6] [2] [4]. Public benchmarking and resolver lists reflect these differences in purpose and performance, and user-facing problems often arise when default or filtered modes clash with user expectations [7] [8].
6. What’s missing from reporting and the practical bottom line
Available sources document the mechanisms — authoritative multi‑IP replies, caching, geo/load-balancing, filtering blocklists and vendor policies — that produce differing results for duckduckgo.com across resolvers, and provide anecdotal user reports of OpenDNS causing access issues [1] [3] [5] [4]. What is not included in the supplied reporting is a synchronized, live test matrix showing current responses from Cloudflare, Google, OpenDNS, Quad9 and DuckDuckGo DNS for duckduckgo.com at specific times and locations; without that live data it is impossible to assert which resolver presently returns a different answer in a given geography [2] [7]. The robust inference: most resolvers return the same authoritative addresses most of the time, but differences arise for technical (caching, geo-DNS), security (blocklists, DNS-level malware/scam blocking) and policy (family/safe-search) reasons, and users seeing inconsistent behavior should test multiple resolvers or check resolver filter settings to diagnose the cause [3] [8].