The bottom line is that DNS queries are very telling metadata. If you were using a VPN and directing DNS queries through the VPN tunnel to another resolver then your ISP would see little, just some (encrypted) VPN traffic. If you're just using an alternate resolver for your DNS queries then your ISP can still pretty much see everything since they carry your Internet traffic. Since I'm already using my own DNS server, did I really keep myīrowsing activities or my ISP still can see it? It further elaborates on the usage of collected data. Look at this Wikipedia page for an example (OpenDNS). So the better question you probably have in mind is, do they exploit the data? Yes. The logs can be archived, purged, rotated depending on corporate policy. Any connection to a website or a mail server leaves a trace in the logs, which can be short-lived, but not always. On the Internet, assume everything is 'logged', meaning: an entry is automatically written to a log file, typically along with some PII (personally identifiable information) like remote IP address and ports.

Since a search engine cannot 'guess' all the websites in existence, the DNS lookups are a great data source. Another obvious source for that is the certificate transparency logs. In the case of actors such as Google, there is one obvious usage: to discover new websites to crawl. Discussion: Understanding DNS sinkholes – A weapon against malware. They may 'censor' queries for protection purposes too, by 'sinkholing' requests to malicious hosts. Essentially, this is a crowdsourced effort. So there is a strong 'threat analysis' aspect here. Note that it can have positive aspects, for example the tracking of malware/ransomware. Why would a commercial venture offer a 'free' service in the first place? It doesn't have to be evil but there is usually a trade-off involved.Ī public DNS service is a large-scale data mining operation of some sort. Do Public DNS servers log our DNS queries?

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