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  1. Rene,

    A good way to explain this subject that is a little confuse.
    About challenge, I tried to solve it…

    A network 10.0.0.0

    One subnet for 600 hosts -> It’s need a block 1024
    One subnet for 250 hosts. -> It’s need a block 256
    One subnet for 120 hosts. -> It’s need a block 128
    One subnet for 30 hosts. -> It’s need a block 32
    One subnet for 2 hosts. -> It’s need a block 4

    A block of 1024 is like 4x256, which is need 10 hosts bits.

    So…

    Subnet 1: (size 1024)

    network address: 10.0.0.0/22
    netmask: 255.255.252.0
    first host: 10.0.0.1
    last host: 10.0.3.254
    broadcast address: 10.0.3.255

    Subnet 2: (size 250)

    network address: 10.0.4.0/24
    netmask: 255.255.255.0
    first host: 10.0.4.1
    last host: 10.0.4.254
    broadcast address: 10.0.4.255

    Subnet 3: (size 120)

    network address: 10.0.5.0/25
    netmask: 255.255.255.128
    first host: 10.0.5.1
    last host: 10.0.5.126
    broadcast address: 10.0.5.127

    Subnet 4: (size 30)

    network address: 10.0.5.128/27
    netmask: 255.255.255.224
    first host: 10.0.5.129
    last host: 10.0.5.158
    broadcast address: 10.0.5.159

    Subnet 5: (size 2)

    network address: 10.0.5.160/30
    netmask: 255.255.255.252
    first host: 10.0.5.161
    last host: 10.0.5.162
    broadcast address: 10.0.5.163

    I hope I’m right…

    When you have a free time, please, fix the details below.
    “Subnet 2: 256 – 32 = <>” so the subnet mask is 255.255.255.224"
    and
    on subnet2 the last host IP should be 172.16.2.254

    Hug and more a time, thanks for excellent work!!!

  2. Hi I’m having hard time figuring out the Subnet Mask, Hosts, Subnets, Network ID and Broadcast ID for the following IP Address. I hope someone can help me answers. Cheers!

    150.12.110.10/25

    112.10.78.40/22

    50.1.112.10/21

    28.10.145.10/18

    150.50.50.50/23

    100.10.185.10/20

    172.16.221.10/19

  3. Hi Lynkaran,

    I’ll explain how to do the first example, see if you can solve them with my technique. Let’s start with 112.10.78.40/22:

    First we need to figure out what the subnet mask since /22 doesn’t tell us much. You need to write this down in binary and convert it to decimal:

    first 8 bits = 11111111 (255 in decimal)
    next 8 bits = 11111111 (255 in decimal)
    next 8 bits = 11111100 (252 in decimal)
    next 8 bits = 00000000 (0 in decimal)

    So now we know the subnet mask is 255.255.252.0

    How many hosts do we have per subnet? There are 2 + 8 host bits so 10 host bits in total. You can use this formula for this:

    210 - 2 = 1024.

    You need to remove 2 since one address is the network address and the other one is the broadcast address.

    What subnets do we have? There’s a quick way to calculate this. Take number 256 - subnet mask = size of subnet:

    256 - 252 = 4

    Now we can write down the subnets, I’ll start with 0:

    #1 112.10.0.0/22
    #2 112.10.4.0/22
    #3 112.10.8.0/22
    #4 112.10.12.0/22
    #5 112.10.16.0/22
    #6 112.10.20.0/22
    #7 112.10.24.0/22
    …and so on

    You can see it increases with 4 every time, you now have your network addresses. What about the broadcast address? That’s the last address in each subnet.

    For subnet #1 that will be 112.10.3.255 and for subnet #5 it’s 112.10.19.255.

    See if you can do the other examples on your own with these steps. All you need is practice, practice, practice.

    Hope this helps.

    Rene

  4. Hello Rahul

    If you were to use three separate subnets to accommodate 600 hosts then you could create them, but they would still be separate subnets. For example, you could use

    192.168.0.0/24
    192.168.1.0/24
    192.168.2.0/24

    That would give you 256*3 = 768 IP addresses.

    However, you would still have three SEPARATE subnets each requiring a network address, a broadcast address and a default gateway. You would also require routing to communicate between the subnets. For example, a host at 192.168.0.26 needs to go through a router to reach 192.168.2.26.

    If you want to create ONE large subnet, you must find the smallest subnet that will accommodate at least 600 hosts.

    So
    a subnet mask of 255.255.255.0 or /24 gives you 255 IPs
    a subnet mask of 255.255.254.0 or /23 gives you 512 IPs
    a subnet mask of 255.255.252.0 or /22 gives you 1024 IPs

    Notice that the sizes of the subnets always double in size so you go from 512 to 1024 addresses. There is no whole subnet that gives you 768 hosts (256*3).

    A subnet mask of 255.255.252.0 or /22 which gives you 1024 IPs is equivalent to the merging of FOUR /24 subnets.

    I hope this has been helpful!

    Laz

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