Update Quad9 logging information and DNS server footnotes (#1001)

docs/dns.en.md

@@ -14,19 +14,20 @@ icon: material/dns
 | DNS Provider | Privacy Policy | Type | Protocols | Logging | ECS | Filtering |
 | ------------ | -------------- | ---- | --------- | ------- | --- | --------- |
 | [**AdGuard**](https://adguard.com/en/adguard-dns/overview.html) | [:octicons-link-external-24:](https://adguard.com/en/privacy/dns.html) | Commercial | Cleartext <br> DoH <br> DoT <br> DNSCrypt | Some[^1] | No | Based on server choice. Filter list being used can be found here. [:octicons-link-external-24:](https://github.com/AdguardTeam/AdGuardDNS)
-| [**Cloudflare**](https://developers.cloudflare.com/1.1.1.1/setting-up-1.1.1.1/) | [:octicons-link-external-24:](https://www.cloudflare.com/privacypolicy) | Commercial | Cleartext <br> DoH <br> DoT | Some[^2] | No | Based on server choice.|
+| [**Cloudflare**](https://developers.cloudflare.com/1.1.1.1/setting-up-1.1.1.1/) | [:octicons-link-external-24:](https://developers.cloudflare.com/1.1.1.1/privacy/public-dns-resolver/) | Commercial | Cleartext <br> DoH <br> DoT | Some[^2] | No | Based on server choice.|
 | [**ControlID**](https://controld.com) | [:octicons-link-external-24:](https://controld.com/privacy) | Commercial | Cleartext <br> DoH <br> DoT | Optional[^3] | No |  Based on server choice.  |
-| [**MullvadDNS**](https://mullvad.net/en/help/dns-over-https-and-dns-over-tls) | [:octicons-link-external-24:](https://mullvad.net/en/help/privacy-policy/) [^4] | Commercial | DoH <br> DoT | No | No | Based on server choice. Filter list being used can be found here. [:octicons-link-external-24:](https://github.com/mullvad/dns-adblock)
+| [**MullvadDNS**](https://mullvad.net/en/help/dns-over-https-and-dns-over-tls) | [:octicons-link-external-24:](https://mullvad.net/en/help/no-logging-data-policy/) | Commercial | DoH <br> DoT | No[^4] | No | Based on server choice. Filter list being used can be found here. [:octicons-link-external-24:](https://github.com/mullvad/dns-adblock)
 | [**NextDNS**](https://www.nextdns.io) | [:octicons-link-external-24:](https://www.nextdns.io/privacy) | Commercial | Cleartext <br> DoH <br> DoT <br> DNSCrypt | Optional[^5] | Optional | Based on server choice. |
-| [**Quad9**](https://quad9.net) | [:octicons-link-external-24:](https://quad9.net/service/privacy) | Non-Profit | Cleartext <br> DoH <br> DoT <br> DNSCrypt | No | Optional |  Based on server choice, Malware blocking by default. |
+| [**Quad9**](https://quad9.net) | [:octicons-link-external-24:](https://quad9.net/privacy/policy/) | Non-Profit | Cleartext <br> DoH <br> DoT <br> DNSCrypt | Some[^6] | Optional |  Based on server choice, Malware blocking by default. |
 
-[^1]: We store aggregated performance metrics of our DNS server, namely the number of complete requests to a particular server, the number of blocked requests, the speed of processing requests. We keep and store the database of domains requested in the last 24 hours. We need this information to identify and block new trackers and threats. We also log how many times this or that tracker has been blocked. We need this information to remove outdated rules from our filters.
-[^2]: Cloudflare collects and stores only the limited DNS query data that is sent to the 1.1.1.1 resolver. The 1.1.1.1 resolver service does not log personal data, and the bulk of the limited non-personally identifiable query data is only stored for 25 hours.
-[^3]: Neither free nor premium service have logging enabled by default. Premium users can enable logging/analytics at will.
-[^4]: Our public DNS service offers DNS over HTTPS (DoH) and DNS over TLS (DoT), with QNAME minimization and basic ad blocking. It has been audited by the security experts at Assured. You can use this privacy-enhancing service even if you don't use Mullvad.
-[^5]: NextDNS can provide insights and logging features on an opt-in basis. Users can choose retention times and log storage locations for any logs they choose to keep.
+[^1]: AdGuard stores aggregated performance metrics of their DNS servers, namely the number of complete requests to a particular server, the number of blocked requests, and the speed of processing requests. They also keep and store the database of domains requested in within last 24 hours. "We need this information to identify and block new trackers and threats." "We also log how many times this or that tracker has been blocked. We need this information to remove outdated rules from our filters." [https://adguard.com/en/privacy/dns.html](https://adguard.com/en/privacy/dns.html)
+[^2]: Cloudflare collects and stores only the limited DNS query data that is sent to the 1.1.1.1 resolver. The 1.1.1.1 resolver service does not log personal data, and the bulk of the limited non-personally identifiable query data is stored only for 25 hours. [https://developers.cloudflare.com/1.1.1.1/privacy/public-dns-resolver/](https://developers.cloudflare.com/1.1.1.1/privacy/public-dns-resolver/)
+[^3]: Neither free nor premium users of ControlD have logging enabled by default. Premium users can enable logging/analytics at will. [https://controld.com/privacy](https://controld.com/privacy)
+[^4]: Mullvad's DNS service is available to both subscribers and non-subscribers of Mullvad VPN. Their privacy policy explicitly claims they do not log DNS requests in any way. [https://mullvad.net/en/help/no-logging-data-policy/](https://mullvad.net/en/help/no-logging-data-policy/)
+[^5]: NextDNS can provide insights and logging features on an opt-in basis. Users can choose retention times and log storage locations for any logs they choose to keep. If not specifically requested by the user, no data is logged. [https://nextdns.io/privacy](https://nextdns.io/privacy)
+[^6]: Quad9 collects some data for the purposes of threat monitoring and response. That data may then be remixed and shared, such as for the purpose of security research. Quad9 does not collect or record IP addresses or other data they deem personally identifiable. [https://www.quad9.net/privacy/policy/](https://www.quad9.net/privacy/policy/)
 
-The criteria for servers for this table are:
+The criteria for the servers listed above are:
 
 - Must support [DNSSEC](technology/dns.md#what-is-dnssec-and-when-is-it-used)
 - Must have [anycast](https://en.wikipedia.org/wiki/Anycast#Addressing_methods) support