Most normal people will probably never even know this is a thing, but Chrome (and other browsers, really) keeps its own in-memory DNS cache, separate from what the OS keeps. For normal use, this is undoubtedly an improvement.
But every now and then, this can be a burden, and Chrome will have cached something you don’t want it to. For example, you make a change in
/etc/hosts to hit a development server bypassing its load balancer or the like, but Chrome has already cached the IP, and thus the
hosts change isn’t picked up.
It turns out that you can totally flush this cache—and view its contents. Just pay a visit to
chrome://net-internals/#dns and voila! A listing of cache entires, and a “Clear host cache” button. (It also provides a look at how many optimistic DNS queries Chrome performs: many of the entries seem to be unvisited links on sites you’ve visited.)