What does DNS cache mean?
A DNS cache stores previous resolution results for a period so repeated lookups need not start from scratch. It can improve efficiency, but a retained answer can temporarily differ from a recently changed service address. Caches exist at several different layers.
Why it matters
App data, operating-system DNS state, router state and upstream resolver caches are not identical. Clearing one does not guarantee all others change immediately. Use the platform's supported procedure for a specific lookup problem. Repeatedly deleting an app profile can remove credentials and favourites without addressing the relevant cache. Keep the supplied hostname correct and report persistent failures.
A practical example
If a provider changes an endpoint, one device may retain an older answer while another obtains a newer one. That is a plausible cache comparison, not a reason to edit signed media URLs manually.
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Related terminology: Dithering, DNS over HTTPS.
For practical setup and troubleshooting, browse the journal or support guides.