Comment 347 for bug 417757

A couple of points:

- almost no server handles two or more requests in one package. Very unfortunate
  but true.

- there always was the option to keep the socket open but hardly any program
  took advantage of this (setting the RES_STAYOPEN flag)

- any solution will punish those broken setups. I'll implement a second fallback.
  If the environment really prevents reuse of the same source port then we'll
  automatically use it only if separate requests on the same port fails.

I really hope that people will file this misbehavior of the routers as bugs. It has always been valid of the DNS library.