In Red Hat Enterprise Linux 7, nc has been replaced with ncat which is a part of nmap. This means some changes in behavior.
1) The portscan feature of nc has been removed, use nmap for that or script it.
2) To do a simple connection test to a port, instead of 'nc -w 3 -z host 123' you can do:
$ echo test|nc -w 3 --send-only host 123
(The command exits with 0 if successful)
That's all for today.