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I am fairly new to networking i have a simple query on how I can work out the network, broadcast, first usable, last usable and the subnet mask for the IP in the title for 9 subnets.

Sam
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    Network classes are dead, killed in 1993 by RFCs 1518 and 1519, which defined CIDR (_Classless_ Inter-Domain Routing). Please let them rest in peace. Modern networking does not use network classes. See [this excellent answer](http://networkengineering.stackexchange.com/a/7117/8499) for how to calculate IPv4 networks. – Ron Maupin Mar 12 '17 at 14:41
  • can you help me pls – Sam Mar 12 '17 at 15:13
  • I gave you a link for how to do that. It explains in detail what you need to do. – Ron Maupin Mar 12 '17 at 15:14
  • yh im fairly new to subnetting so id prefer someone actually helping my situation pls, if you cant then no problem – Sam Mar 12 '17 at 15:16
  • There is nothing anyone could add to that answer. It explains how to do everything you asked. What other help would you need? – Ron Maupin Mar 12 '17 at 15:17
  • so basically i have that ip address and i need to find the network, broadcast, first usable, last usable address for the 16 bits to accommodate for the 9 subnets in my situation – Sam Mar 12 '17 at 15:19
  • Right, and the answer I linked explains in detail how to do that. – Ron Maupin Mar 12 '17 at 15:20
  • how do i get the size of the subnet – Sam Mar 12 '17 at 15:26
  • to accommodate for the 200 hosts in my situation – Sam Mar 12 '17 at 15:26
  • Again, read the answer, it explains how to do that. – Ron Maupin Mar 12 '17 at 15:28
  • pls can you just help me, i have read it and got the addresses but i need to accommodate for the no. of hosts too in each subnet – Sam Mar 12 '17 at 15:31
  • As I wrote, I cannot add anything to that answer. I would tell you exactly the same thing. Just convert everything to binary, then it becomes obvious. do your calculations, then convert back to decimal. There really isn't anything more to it. – Ron Maupin Mar 12 '17 at 15:33
  • i needed help on subnettting based on host requirements – Sam Mar 12 '17 at 15:56
  • can you help me pls daniel – Sam Mar 12 '17 at 16:19
  • im really struggling here – Sam Mar 12 '17 at 16:19
  • The thread suggested by Daniel B seems to address what you're asking. Can you clarify what isn't clear after reading that thread? That will help people respond in a useful way. – fixer1234 Mar 12 '17 at 21:29

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There are many online sites that provide tools to perform subnet calculations that you can find by searching on "subnet calculator" or "subnet calculator cidr". E.g., go to CIDR / VLSM Supernet Calculator and put 172.16.0.0 in the IP address field and then select 255.255.240.0, which corresponds to a /20, in the CIDR netmask field. Or, specifically for 172.16.0.0/20 at IP Calculator. There are also online courses that will teach you how to perform such calculations yourself, e.g., Udemy offers Subnetting Made Super Simple (current cost $15 USD) and other courses on the topic.

moonpoint
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  • i need help on subentting based on hosts – Sam Mar 12 '17 at 16:29
  • for each subnet, each sybnet hs different number oif hosts – Sam Mar 12 '17 at 16:30
  • You put "172.16.0.0/20" in the subject of your message, which gives you up to 4,096 subnets. Of course, if you only need 9 subnets, that's far more than you need. What difference does it make to you if one subnet actually has more IP addresses allocated to hosts in that subnet than another? – moonpoint Mar 12 '17 at 16:36
  • @moonpoint, why do you say, "_gives you up to 4,096 subnets_?" If you use `/21` subnets, then you only have two subnets, or if you use `/31` subnets, then you can have 2048 subnets. The 4096 number is actually the number of hosts in a `/20` network. – Ron Maupin Mar 12 '17 at 16:40
  • i need to find network address broadcast address and the usable range for each subnet – Sam Mar 12 '17 at 16:45
  • BUT each subnet has differenet number of hosts – Sam Mar 12 '17 at 16:45
  • this is where im struggling – Sam Mar 12 '17 at 16:45
  • get the addresses for different number of hosts in each subnet – Sam Mar 12 '17 at 16:46
  • @Ron Maupin It was an error; thanks for the correction. – moonpoint Mar 12 '17 at 16:50
  • @Sam, the link I provided you spells out how to do everything you are asking. There is even a section titled **Finding the required subnet masklength or netmask** that tells you how to determine the required size for the number of hosts. What is your problem with it, or are you simply wanting someone to do your work for you, even though you asked how? – Ron Maupin Mar 12 '17 at 16:54
  • i didnt read that title, i thought it meant something different, ill read it now – Sam Mar 12 '17 at 17:05
  • @Sam, if you want to know how to do this stuff, you need to read and understand the entire answer. It is all inter-related. It explains everything you need to know about calculating IPv4 networks. – Ron Maupin Mar 12 '17 at 17:36