Since the 4.2.8 upgrade, ntpd is broken on NixOS: Dec 28 19:06:54 hagbard ntpd[27723]: giving up resolving host 1.nixos.pool.ntp.org: Servname not supported for ai_socktype (-8) This appears to be because DNS resolution doesn't work in chroots anymore (due to /etc being missing). So disable chroots for now. It's probably better to use systemd's containment facilities anyway.
*** NixOS *** NixOS is a Linux distribution based on the purely functional package management system Nix. More information can be found at http://nixos.org/nixos and in the manual in doc/manual.