Jens, I ran your program ("updated test") on a Debian 7.0 system with libc6 et al upgraded to 2.17-7.
Output: y.c:44: error: r=-2 Name or service not known Output after replacing "karme.de." with "www.google.com": none; the program completed successfully. Output after doing "iptables -I OUTPUT -p udp -m udp --dport 53 -j DROP": y.c:29: error: r=-5 No address associated with hostname Comments? -- Thomas