By the way just do want to mention if nc was missing with in earlier versions of zimbra hows that zmconfigd was not giving error
infact I do have a zimbra version 7.1.0 and nc missing but no errors at all
working just grt.
I guess this has to be mentiond in pre requesites
have you installed the patch for 7.11.
does which nc show in /usr/bin/nc