DNS Update Monitor
Reference: how long does DNS propagation take?
A changed DNS record is visible immediately on the authoritative nameservers (usually within seconds of saving it at your DNS host). Every other resolver keeps serving the old value until its cached copy expires, which takes at most the old TTL (time-to-live) of the record. There is no global "propagation": each resolver refreshes on its own schedule.
| Resolver | When does it show the new value? | Can you force a refresh? |
|---|---|---|
| Authoritative nameservers (e.g. Gandi, Cloudflare, Route 53) | Seconds to a few minutes after you save the record | Not needed |
| 🇺🇸 Google Public DNS (8.8.8.8) | When the cached record's TTL expires (this tool shows the remaining seconds) | Yes: Google flush cache |
| 🇺🇸 Cloudflare DNS (1.1.1.1) | When the cached record's TTL expires | Yes: Cloudflare purge cache |
| 🇩🇪 DNS.SB (185.222.222.222) | When the cached record's TTL expires; anycast, operated from Düsseldorf | No |
| 🇨🇳 AliDNS (223.5.5.5) | When the cached record's TTL expires; shows what users in China see | No |
| Your ISP's resolver | When the TTL expires; some ISPs enforce a minimum cache time of 300 to 3600 s | No |
| Your computer / browser | OS cache: TTL; Chrome: up to 1 minute | Yes: ipconfig /flushdns (Windows), sudo dscacheutil -flushcache (macOS), chrome://net-internals/#dns |
| Nameserver (NS) change at the registrar | Up to 24 to 48 hours: the .com/.net zones use a 172800 s (48 h) TTL for NS records | No |
- Lower the TTL before you change the record: set it to 300 s at least one old-TTL period in advance, so the switch itself takes only 5 minutes.
- An A record with a TTL of 3600 s (1 hour) can stay cached for up to 60 minutes after the change; with a TTL of 86400 s (1 day) for up to 24 hours.
- This tool queries Google, Cloudflare, DNS.SB and AliDNS via DNS-over-HTTPS straight from your browser, and the authoritative servers through toolstud.io. Every 10 seconds, for at most 10 minutes.
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Frequently Asked Questions
Why do Google and Cloudflare still show the old IP address?
Public resolvers cache every answer for the record's TTL (time-to-live). Until that cached copy expires they keep returning the old value. The TTL column of this tool shows how many seconds are left. Google and Cloudflare both offer a public "flush cache" page if you cannot wait.
The authoritative nameserver already shows the new value, but my browser does not. Why?
Your operating system, your browser and your ISP's resolver all keep their own DNS cache. Flush the local cache (ipconfig /flushdns on Windows, sudo dscacheutil -flushcache on macOS) and wait for the ISP resolver's TTL to expire. You cannot flush an ISP resolver yourself.
How long does DNS propagation take?
At most the old TTL of the record: 5 minutes for a 300 s TTL, 1 hour for 3600 s, 24 hours for 86400 s. Nameserver (NS) changes at the registrar can take up to 48 hours because the top-level domain zones use a 172800 s TTL. Lower the TTL before making a change to speed this up.
Does this tool query my ISP's resolver?
No. A web page can only reach DNS servers that speak DNS-over-HTTPS with CORS enabled: Google, Cloudflare, DNS.SB and AliDNS. The authoritative nameservers of your domain are queried through toolstud.io with dig. OpenDNS, Quad9 and AdGuard send no CORS header and cannot be polled from a web page. Your ISP's resolver can only be checked from your own computer, e.g. with dig or nslookup.
What is DNS-over-HTTPS (DoH)?
DNS-over-HTTPS sends DNS queries as HTTPS requests instead of plain UDP packets on port 53. Google (dns.google) and Cloudflare (cloudflare-dns.com) expose a JSON version of it, which is what lets this page poll them directly from your browser without any server in between.
