Please consider updating pdns-recursor in Leap 42.3.
For example it has now full DNSSEC support and has quite some performance improvements

- use individual libboost-*-devel packages instead of boost-devel
- add signature file for upstream release

- update to version 4.0.4
The following security advisories were fixed
- 2016-02: Crafted queries can cause abnormal CPU usage
(CVE-2016-7068, boo#1018326)
- 2016-04: Insufficient validation of TSIG signatures
(CVE-2016-2120, boo#1018329)
complete changeset is availalbe at,
https://doc.powerdns.com/md/changelog/#powerdns-recursor-404
- remove 4462.patch: in upstream release.

- BuildRequire pkgconfig(libsystemd) instead of
pkgconfig(libsystemd-daemon): these libs were merged in systemd
209 times. The build system is capable of finding either one.

- 4462.patch:
Disable fcontext usage with Boost 1.61+ and revert back to
slower SystemV ucontext. This fixes failure to build with
newer Boost version. (boo#998408)

- update to 4.0.3
A new release for the PowerDNS Recursor with version 4.0.3 is
available. This release has many fixes and improvements in the
Policy Engine (RPZ) and the Lua bindings to it. Therefore, we
recommend users of RPZ to upgrade to this release. We would like
to thank Wim (42wim on github) for testing and reporting on the
RPZ module.
Bug fixes