If turn config.proxy.hostdb off, ts does not do the dns query but just return a 502 page.
Hmmm, i think this is "by design" at this point :-/. I'm going to move this out to v3.3.0 for now, if someone else wish to work on this (I think it'd require some major re-factoring of the code), please feel to re-prioritize.
What ought to happen here? Remove the proxy.config.hostdb option?
Maybe there's a use case where in transparent proxy, with certain configs, the UA (browser) actually does the DNS lookup? I can't see this being useful to disable though with forward or reverse proxy.
Also, looking at the code, the intent was probably to do a DNS lookup on every request (perhaps a local, caching resolver). So this does indeed seem like a valid bug, although not sure how usable it would be.
Moving to 4.2.0 as per https://cwiki.apache.org/confluence/display/TS/New+Release+Processes
I'm thinking we should close this as Won't Fix, in favor of upcoming refactoring of HostDB. Any objections?
No objections, so closing.