Right after fixing the host file issue, this came up.

Turns out CentOS no longer uses the standalone nc package, instead installs it as part of the nmap-ncat package. While this package was already installed and nc running fine, Zimbra appears to be looking for it through yum list which actually says that the package is not installed and is available.

To get around this I dropped nc from the detection list. To do this, navigate to the directory where Zimbra‘s install files are extracted, then head into util and edit utilfunc.sh. Go to line 2503 and remove nc from that line.