[outages] Some .de DNS servers returning NXDOMAIN

It appears that part of the .de zone is missing from their name servers resulting in NXDOMAIN for valid queries. "It depends on the domain name. Before the letter F (denic.de, bund.de, bild.de) everything works. After (google.de, tageszeitung.de, heise.de), it fails." https://lists.dns-oarc.net/pipermail/dns-operations/2010-May/005530.html