With debug logging on the router lots every DNS lookup it makes. However it does not say if the request was successful or failed or any info other then the actual lookup.
Example
{"timestamp":"2022-12-30T00:36:40.661465Z","level":"DEBUG","fields":{"message":"resolving host=\"uplink.api.apollographql.com\""},"target":"hyper::client::connect::dns"}
This ends up filling the logs with uninformative clutter that is not useful for any sort of operational debugging of lookups.