When doing any moderate to advanced networking, you are likely to have to deal with subnetting. While some people have an ability to do the binary math in their head to figure out the correct subnet-mask, I prefer to use a tool to give me the answer. I have used “ipcalc” on my FreeBSD machines for years, to give me the answers to my subnetting problems. I recently tried to use the ipcalc tool on my Fedora machine and found it to be completely different. Apparently RedHat has developed their own ipcalc tool, with the same name as another project. It is not terribly surprising that this situation could have happened, as both projects attempt to provide similar information.
In my humble opinion the RedHat ipcalc is not nearly as informative as the tool created by Krischan Jodies found at: http://jodies.de/ipcalc At their site they provide an online version, for quick access. If you want to download the tool for use on a Linux/Unix machine, it can be found at: http://jodies.de/ipcalc-archive/
[username@host ~]$ ipcalc 192.168.1.0/13 -m
You have to basically use a different flag for each piece of information. In general you probably already know all the information if you're able to get this far.
Krischan Jodies ipcalc:
[username@host ~]$ bin/ipcalc 192.168.1.0/13
Address: 192.168.1.0 11000000.10101 000.00000001.00000000
Netmask: 255.248.0.0 = 13 11111111.11111 000.00000000.00000000
Wildcard: 0.7.255.255 00000000.00000 111.11111111.11111111
Network: 192.168.0.0/13 11000000.10101 000.00000000.00000000
HostMin: 192.168.0.1 11000000.10101 000.00000000.00000001
HostMax: 18.104.22.168 11000000.10101 111.11111111.11111110
Broadcast: 22.214.171.124 11000000.10101 111.11111111.11111111
Hosts/Net: 524286 Class C, In Part Private Internet
While the RedHat version may not necessarily be trying to compete with Jodies version, I think that Jodies is far more informative.