Does HostnameLookups add latency before or after the response is sent?

Question

It was my understanding that HostnameLookups adds latency to only the completion of the request. So a thread that could answer a new request would be blocked until the thread completed the lookup.

However, the Apache documentation reads:

It is also better for the end users because they don't have to suffer the extra latency that a lookup entails.

Does that mean the visitor receives no response data until the lookup is complete? I understand it adds latency to the request, I just don't know to which end, before the response is sent or after.

Answer 1

The response doesn't come until the request is fully processed, so yes, the latency occurs before the response is sent.