VLSM question?

If the required hosts for a certain department is 348 on 172.20.0.0 network what would be the # of host bits to accommodate the given host and would be the SM (subnet mask)?
VLSM question?
VLSM is kinda hard stuff...been a little while but lets see if i can do this off the top of my head. You are dealing with a class A stealing a bit so Class A enhanced address scheme. Now the best way is to use the SUBNET, not the GATEWAY to get this answer. C = 255.255.255.0 B = 255.255.0.0 A= 255.0.0.0





C lets you have 256-2 = 254 hosts.


B = 256 * 256 - 2 = 65534 hosts


A = 256*256*258 - 2 = 16 million and some hosts


So an custom subnet to fullfill 348 hosts would worked out like this...





256...not enough so that rules out class C. 65534 hosts is WAAAAAY to many so it must be between B and C. That's a good start. incremements go as such...256,128,64,32,16,8,4,2,1.. and the subnetting would go inversly to the above So you want the 256 + the 128 to meet what you need.





I'd say the subnet 255.255.128.0 would do it for you. You can also download a subnet calculator to help learn. this was done all in my head, so dont trust it 100%. But the idea is to understand how to do VLSM. Once you get it, the rest is no problems.





I would say you are working on your CCNA...GOOD LUCK! Its rough at first, but you'll get it.