What Does Cache Flush on Google Public DNS Do?

Cache Flush on Google Public DNS asks Google's resolvers to discard cached DNS records for a domain you specify, so the next lookup is fetched fresh from authoritative name servers. It is useful when a domain's records have changed but Google Public DNS still returns the old answer. It does not change your domain's DNS configuration, and it does not clear the cache on your own device, router, or ISP resolver.

What Cache Flush actually does

Google Public DNS caches answers to reduce lookup time and load on authoritative servers. Each cached record has a TTL (time to live) set by the domain's owner. Until that TTL expires, Google's resolvers can keep serving the cached copy.

Cache Flush submits a request to Google Public DNS to remove cached records for a specific domain name. After that, the next query for the domain is resolved again from the authoritative name servers, so a recent record change can appear sooner than waiting for the TTL to run out.

The dns.google page lists Cache Flush alongside Resolve and Help, and the Resolve tool accepts a domain like example.com or an IP address like 8.8.8.8 or 2001:4860:4860::8844. Cache Flush is the part of that toolkit aimed at refreshing cached records rather than looking them up.

When to use it

Use Cache Flush when all of these are true:

• You changed DNS records for a domain (for example, a new A, AAAA, or CNAME target).
• You are checking the result through Google Public DNS (8.8.8.8, 8.8.4.4, or 2001:4860:4860::8888 / ::8844).
• Google Public DNS still returns the old value while the authoritative servers already return the new one.

A typical sequence:

1. Update the record at your DNS provider.
2. Confirm the authoritative name servers return the new value.
3. Query the domain through Google Public DNS and see whether it still returns the old value.
4. If it does, submit a Cache Flush for that domain.
5. Query again and check whether the new value appears.

If the authoritative servers still return the old value, Cache Flush will not help — the problem is upstream of Google's cache.

Cache Flush vs. waiting for TTL

These are separate caches. Flushing Google's cache does not flush your operating system's cache, your browser's cache, or your router's cache, and vice versa. If a stale answer comes from your own device, Cache Flush on dns.google will not fix it.

What Cache Flush does not do

• It does not modify the domain's DNS records. Records are controlled at your DNS provider or authoritative name servers.
• It does not change TTL values. TTLs are set by the domain owner.
• It does not guarantee an instant global update. Other resolvers, and other Google Public DNS locations, may still hold cached copies until their TTLs expire.
• It does not clear caches on your device, browser, router, or ISP.

Common snags

• The record still looks old after flushing. Check the authoritative name servers directly. If they return the old value, the change has not propagated to them yet.
• Only some queries show the new value. Different resolvers and different Google Public DNS nodes can be at different cache states; results may vary until TTLs expire everywhere.
• You flushed but your browser still shows the old site. That is a local or browser cache issue, not a Google Public DNS cache issue.
• You are not using Google Public DNS. Cache Flush only affects Google's resolvers. If your device is configured to use another resolver, flushing Google's cache will not change what you see.

Quick check

Before flushing, verify where the stale answer is coming from. Query the domain through Google Public DNS and compare it with a direct query to the authoritative name servers. If Google is stale and the authoritative servers are current, Cache Flush is the right tool. If both are stale, wait for the change to reach the authoritative servers first.