How does Subnetting Work?
Amazon's elastic compute tool (among others) requires the ip block format for their command:
ec2-authorize websrv -P tcp -p 80 -s 18.104.22.168/16
I may be doing this wrong, but as far as I can tell I need to use the block format even for a single IP address. 1) So, how would I do that for this IP?
Several years ago I took a CCNA class, and I remember going over IPs and subnets, masks, broadcast addresses, class a/b/c networks, etc. However a lot seems to have changed since then - for example I don't think you can tell what "class" a network is in just by looking at it anymore - sometimes they could be multiple classes.
2) Anyhow, my second question is where do I go to get a refresher on all these things?
3) Or should I just be using
ipcalc or an online calculator to do it all for me - and if so, which one?