I propose to update pdns on 42.2 to the current Factory version.
Looking at the changelog I guess it makes sense as there are no real incompatibilities visible

- update to 3.4.9
* use OpenSSL for ECDSA signing where available
* allow common signing key
* Add a disable-syslog setting
* fix SOA caching with multiple backends
* whitespace-related zone parsing fixes [ticket #3568]
* bindbackend: fix, set domain in list()

- update to 3.4.8
* Use AC_SEARCH_LIBS (Ruben Kerkhof)
* Check for inet_aton in libresolv (Ruben Kerkhof)
* Remove hardcoded -lresolv, -lnsl and -lsocket (Ruben Kerkhof)
* pdnssec: don't check disabled records (Pieter Lexis)
* pdnssec: check all records (including disabled ones)
only in verbose mode (Kees Monshouwer)
* traling dot in DNAME content (Kees Monshouwer)
* Fix luabackend compilation on FreeBSD i386 (RvdE)
* silence g++ 6.0 warnings and error (Kees Monshouwer)
* add gcc 5.3 and 6.0 support to boost.m4 (Kees Monshouwer)

- update to 3.4.7
Bug fixes:
* Ignore invalid/empty TKEY and TSIG records (Christian Hofstaedtler)
* Don't reply to truncated queries (Christian Hofstaedtler)
* don't log out-of-zone ents during AXFR in (Kees Monshouwer)
* Prevent XSS by escaping user input. Thanks to Pierre Jaury and Damien
Cauquil at Sysdream for pointing this out.
* Handle NULL and boolean properly in gPGSql (Aki Tuomi)
* Improve negative caching (Kees Monshouwer)
* Do not divide timeout twice (Aki Tuomi)