Unbound, stubby or dnscrypt-proxy

General
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Google does.

What does Quad9 log/store about the DNS queries?

We store details of the DNS records queried, timestamp, and the city, state, and country from where the query came. We do not store source IP information of end-user queries.

Cloudflare will collect only the following anonymized DNS query data that is sent to the Cloudflare Resolver:

Timestamp
IP Version (IPv4 vs IPv6)
Cloudflare Resolver IP address + Destination Port
Protocol (TCP, UDP, TLS or HTTPS)
Query Name
Query Type
Query Class
Query Rd bit set
Query Do bit set
Query Size
Query EDNS enabled
EDNS Version
EDNS Requested Max Buffer Size
EDNS Nsid
Response Type (normal, timeout, blocked)
Response Code
Response Size
Records in Response
Response Time in Milliseconds
Response served from Cache
DNSSEC Validation State (secure, insecure, bogus, indeterminate)
PoP ID
Server ID
Autonomous System Number

Except for the three DNS query types discussed below, all of the log information above will be deleted within 24 hours of Cloudflare’s receipt of such information.