Resolves #1937

(cherry picked from commit bf041070)

(cherry picked from commit 9e4eb182)

(cherry picked from commit f1f188f8)

respondd address

(cherry picked from commit c612dfba)

(cherry picked from commit 1e66cd90)

Uncovered by sphinx-build:
docs/releases/v2018.2.1.rst:19: WARNING: Too many autonumbered footnote references: only 0 corresponding footnotes available.
docs/releases/v2018.2.1.rst:19: WARNING: Unknown target name: "noibss".
docs/releases/v2018.2.1.rst:26: WARNING: Unknown target name: "noibss".
docs/releases/v2018.2.1.rst:30: WARNING: Unknown target name: "noibss".
docs/releases/v2018.2.1.rst:34: WARNING: Unknown target name: "noibss".
docs/releases/v2018.2.1.rst:35: WARNING: Unknown target name: "noibss".

fixes #1561

Fixes: #1463

dnsmasq's caching is severly broken and does not handle all answer records
equally. In particular, its cached answers are missing DNSKEY and DS
records, breaking DNSSEC validation on clients.

Remove the cache for now. It may return if dnsmasq is fixed or we switch to
a different resolver.