Subnetting moment of duh

pwjohnston

I’ve obviously missed this somewhere. Can you guys direct me to a chapter to read in the Odom book or something online?

If you give me an IP and a Subnet Mask (dot decimal or slash) I can derive decimal subnet, ip range, broadcast, no problem. RP-6C is practically ingrained in me by now I hope. I can convert binary to base 10. I can usually derive the Network bits, subnet bits, and host bits from a subnet mask and tell you how many subnets and hosts can be created.

But I keep running into a question where is says something like;

Given a subnet mask (insert any mask) which of the following addresses can be assigned to network hosts?

Then I’m given a list of (valid IPv4) hosts IPs and no network IP.

Where am I going wrong here?

binargs

most of those times the question asks to to know which of the given address can not be a host, so the list of addresses can be either network numbers or bcast numbers. use the subnet knowledge to find out which ones are invalidl.