Most people never choose a DNS resolver at all — their device simply uses whatever their ISP automatically provisions. That default is a real choice with real tradeoffs, even though it doesn't feel like one.
Why ISP DNS is the default
When your router connects to your ISP, it typically receives DNS resolver addresses automatically as part of the connection setup — no configuration required, which is exactly why most people never think about it. This automatic provisioning is convenient by design.
The performance case for it
An ISP's own resolver often has strong network proximity to their own customers and may cache content specific to services they partner with, sometimes making it genuinely fast for local and regional content compared to a distant public alternative.
The privacy and policy considerations
ISP DNS logging and retention policies vary and aren't always as clearly published as major public resolvers' policies tend to be. Some ISPs have historically used DNS-level redirection for advertising or search-result injection on failed lookups — a practice that's declined but hasn't universally disappeared. Some jurisdictions require ISPs to implement DNS-level content filtering for certain categories, which can affect what resolves at all.
How to decide if switching makes sense
If you're satisfied with your ISP's performance and comfortable with their stated (or unstated) privacy practices, there's no requirement to switch. If you want clearer logging policies, encrypted transport support, or specific filtering behavior, comparing your ISP's actual policy against alternatives like those in Public DNS Resolvers is worth the research.
FAQ
How do I find out my ISP's DNS logging policy?
Check their published privacy policy specifically for DNS or network-logging sections — not all ISPs disclose this clearly, which is itself useful information when deciding whether to switch.