Major Network = 10.15.0.0/22
11111111.11111111.11111100.00000000
Number of networks = 2^ 6 = 64
Network Address | Usable Host Range | Broadcast Address: |
10.15.0.0 | 10.15.0.1 – 10.15.3.254 | 10.15.3.255 |
10.15.4.0 | 10.15.4.1 – 10.15.7.254 | 10.15.7.255 |
10.15.8.0 | 10.15.8.1 – 10.15.11.254 | 10.15.11.255 |
10.15.12.0 | 10.15.12.1 – 10.15.15.254 | 10.15.15.255 |
10.15.16.0 | 10.15.16.1 – 10.15.19.254 | 10.15.19.255 |
10.15.20.0 | 10.15.20.1 – 10.15.23.254 | 10.15.23.255 |
10.15.24.0 | 10.15.24.1 – 10.15.27.254 | 10.15.27.255 |
10.15.28.0 | 10.15.28.1 – 10.15.31.254 | 10.15.31.255 |
10.15.32.0 | 10.15.32.1 – 10.15.35.254 | 10.15.35.255 |
10.15.36.0 | 10.15.36.1 – 10.15.39.254 | 10.15.39.255 |
10.15.40.0 | 10.15.40.1 – 10.15.43.254 | 10.15.43.255 |
10.15.44.0 | 10.15.44.1 – 10.15.47.254 | 10.15.47.255 |
10.15.48.0 | 10.15.48.1 – 10.15.51.254 | 10.15.51.255 |
10.15.52.0 | 10.15.52.1 – 10.15.55.254 | 10.15.55.255 |
10.15.56.0 | 10.15.56.1 – 10.15.59.254 | 10.15.59.255 |
10.15.60.0 | 10.15.60.1 – 10.15.63.254 | 10.15.63.255 |
10.15.64.0 | 10.15.64.1 – 10.15.67.254 | 10.15.67.255 |
10.15.68.0 | 10.15.68.1 – 10.15.71.254 | 10.15.71.255 |
10.15.72.0 | 10.15.72.1 – 10.15.75.254 | 10.15.75.255 |
10.15.76.0 | 10.15.76.1 – 10.15.79.254 | 10.15.79.255 |
10.15.80.0 | 10.15.80.1 – 10.15.83.254 | 10.15.83.255 |
10.15.84.0 | 10.15.84.1 – 10.15.87.254 | 10.15.87.255 |
10.15.88.0 | 10.15.88.1 – 10.15.91.254 | 10.15.91.255 |
10.15.92.0 | 10.15.92.1 – 10.15.95.254 | 10.15.95.255 |
10.15.96.0 | 10.15.96.1 – 10.15.99.254 | 10.15.99.255 |
10.15.100.0 | 10.15.100.1 – 10.15.103.254 | 10.15.103.255 |
10.15.104.0 | 10.15.104.1 – 10.15.107.254 | 10.15.107.255 |
10.15.108.0 | 10.15.108.1 – 10.15.111.254 | 10.15.111.255 |
10.15.112.0 | 10.15.112.1 – 10.15.115.254 | 10.15.115.255 |
10.15.116.0 | 10.15.116.1 – 10.15.119.254 | 10.15.119.255 |
10.15.120.0 | 10.15.120.1 – 10.15.123.254 | 10.15.123.255 |
10.15.124.0 | 10.15.124.1 – 10.15.127.254 | 10.15.127.255 |
10.15.128.0 | 10.15.128.1 – 10.15.131.254 | 10.15.131.255 |
10.15.132.0 | 10.15.132.1 – 10.15.135.254 | 10.15.135.255 |
10.15.136.0 | 10.15.136.1 – 10.15.139.254 | 10.15.139.255 |
10.15.140.0 | 10.15.140.1 – 10.15.143.254 | 10.15.143.255 |
10.15.144.0 | 10.15.144.1 – 10.15.147.254 | 10.15.147.255 |
10.15.148.0 | 10.15.148.1 – 10.15.151.254 | 10.15.151.255 |
10.15.152.0 | 10.15.152.1 – 10.15.155.254 | 10.15.155.255 |
10.15.156.0 | 10.15.156.1 – 10.15.159.254 | 10.15.159.255 |
10.15.160.0 | 10.15.160.1 – 10.15.163.254 | 10.15.163.255 |
10.15.164.0 | 10.15.164.1 – 10.15.167.254 | 10.15.167.255 |
10.15.168.0 | 10.15.168.1 – 10.15.171.254 | 10.15.171.255 |
10.15.172.0 | 10.15.172.1 – 10.15.175.254 | 10.15.175.255 |
10.15.176.0 | 10.15.176.1 – 10.15.179.254 | 10.15.179.255 |
10.15.180.0 | 10.15.180.1 – 10.15.183.254 | 10.15.183.255 |
10.15.184.0 | 10.15.184.1 – 10.15.187.254 | 10.15.187.255 |
10.15.188.0 | 10.15.188.1 – 10.15.191.254 | 10.15.191.255 |
10.15.192.0 | 10.15.192.1 – 10.15.195.254 | 10.15.195.255 |
10.15.196.0 | 10.15.196.1 – 10.15.199.254 | 10.15.199.255 |
10.15.200.0 | 10.15.200.1 – 10.15.203.254 | 10.15.203.255 |
10.15.204.0 | 10.15.204.1 – 10.15.207.254 | 10.15.207.255 |
10.15.208.0 | 10.15.208.1 – 10.15.211.254 | 10.15.211.255 |
10.15.212.0 | 10.15.212.1 – 10.15.215.254 | 10.15.215.255 |
10.15.216.0 | 10.15.216.1 – 10.15.219.254 | 10.15.219.255 |
10.15.220.0 | 10.15.220.1 – 10.15.223.254 | 10.15.223.255 |
10.15.224.0 | 10.15.224.1 – 10.15.227.254 | 10.15.227.255 |
10.15.228.0 | 10.15.228.1 – 10.15.231.254 | 10.15.231.255 |
10.15.232.0 | 10.15.232.1 – 10.15.235.254 | 10.15.235.255 |
10.15.236.0 | 10.15.236.1 – 10.15.239.254 | 10.15.239.255 |
10.15.240.0 | 10.15.240.1 – 10.15.243.254 | 10.15.243.255 |
10.15.244.0 | 10.15.244.1 – 10.15.247.254 | 10.15.247.255 |
10.15.248.0 | 10.15.248.1 – 10.15.251.254 | 10.15.251.255 |
10.15.252.0 | 10.15.252.1 – 10.15.255.254 | 10.15.255.255 |
Number of hosts per network = 2^10 – 2 = 1022
Requirements:
Required # of Hosts | Total # of Hosts based on host bits derived | Use |
500 hosts | 510 | Guest |
200 hosts | 254 | Sales |
100 hosts | 126 | Engineering |
50 hosts | 62 | Finance |
15 hosts | 30 | Future use |
15 hosts | 30 | Future use |
The Total # of hosts required = 880 | The total # of hosts allotted = 1,012 |
Total number of networks:
Using the following info, obtain the host bits and subnets
2^9 | 512 | /23 | 11111111.11111111.11111110.00000000 | 255.255.254.0 |
2^8 | 256 | /24 | 11111111.11111111.11111111.00000000 | 255.255.255.0 |
2^7 | 128 | /25 | 11111111.11111111.11111111.10000000 | 255.255.255.128 |
2^6 | 64 | /26 | 11111111.11111111.11111111.11000000 | 255.255.255.192 |
Start with the first network based on the bitmask > note that the subnet mask will change.
The original IP block of 10.15.0.0/22 will produce 1022 usable hosts. The largest host requirement is 500 hosts, which equates to a /23. The original/22 can be broken down into two /23 subnets, which will produce 510 hosts each.
An increment of 2 is derived from the following bit mask where the “last” 1 bit is in the “2” column.
128 | 64 | 32 | 16 | 8 | 4 | 2 | 1 |
1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 |
1st network assignment
Start with the given IP range of 10.15.0.0 and increment the third octet by two, which will produce 10.15.2.0.
The second network begins with 10.15.2.0/23, which means that you will subtract one from the third octet to produce the “end” IP range of the first network. Remember that the original network was divided into two.
Network | Bitmask | Inc | Ist IP | Last IP | Broadcast Address | SM |
10.15.0.0/23 | 11111111.11111111.11111110.00000000 | 2 | 10.15.0.1 | 10.15.1.255 | 10.15.1.255 | 255.255.254.0 |
10.15.2.0/23 | 11111111.11111111.11111110.00000000 | 2 | N/A | N/A | N/A | N/A |
2nd network assignment
The second requirement is 200 hosts. The second subnet begins with 10.15.2.0/23, which will produce 510 hosts. The network can be further subdivided into two /24 networks, which will increment by 1 based on the bitmask as outlined in the table below.
Network | Bitmask | Inc | Ist IP | Last IP | Broadcast Address | SM |
N/A | N/A | N/A | N/A | N/A | ||
10.15.2.0/24 | 11111111.11111111.11111111.00000000 | 1 | 10.15.2.1 | 10.15.2.254 | 10.15.2.255 | 255.255.255.0 |
10.15.3.0/24 | 11111111.11111111.11111111.00000000 | 1 | Unused | Unused | Unused | Unused |
The second network begins with 10.15.2.0/24, which means that you will subtract one from the third octet to produce the “end” IP range of the second network.
3rd network assignment
The third requirement is 100 hosts. The third subnet begins with 10.15.3.0/24, which will produce 256 hosts. The network can be further subdivided into two /25 networks, which will increment by 128 based on the bitmask as outlined in the table below.
Network | Bitmask | Inc | Ist IP | Last IP | Broadcast Address | SM |
N/A | N/A | N/A | 10.15.2.255 | N/A | ||
10.15.3.0/25 | 11111111.11111111.11111111.10000000 | 128 | 10.15.3.1 | 10.15.3.126 | 10.15.3.127 | 255.255.255.128 |
10.15.3.128/25 | 11111111.11111111.11111111.10000000 | 128 | Unused | Unused | Unused | Unused |
The third network begins with 10.15.3.0/25, which means that you will subtract one from the fourth octet to produce the “end” IP range of the third network.
4th network assignment
The fourth requirement is 50 hosts. The third subnet begins with 10.15.3128/25, which will produce 128 hosts. The network can be further subdivided into two /26 networks, which will increment by 64 based on the bitmask as outlined in the table below.
Network | Bitmask | Inc | Ist IP | Last IP | Broadcast Address | SM |
1 | 11111111.11111111.11111111.10000000 | NA | NA | NA | NA | NA |
10.15.3.128/26 | 11111111.11111111.11111111.11000000 | 64 | 10.15.3.129 | 10.15.3.190 | 10.15.3.191 | 255.255.255.192 |
10.15.3.192/26 | 11111111.11111111.11111111.11000000 | 64 | Unused | Unused | Unused | Unused |
The remaining networks for future use
The remaining subnet(s) will begin at 10.15.3.192/26, which can be incremented by “64”, which will produce a subnet with 62 hosts, or it can be broken down one final time to a /27, which will produce 30 hosts each.
Network | Bitmask | Inc | Ist IP | Last IP | Broadcast Address | SM |
10.15.3.192/26 | 11111111.11111111.11111111.11000000 | 64 | 10.15.3.192 | 10.15.3.254 | 10.15.3.255 | 255.255.255.192 |
OR
Network | Bitmask | Inc | Ist IP | Last IP | Broadcast Address | SM |
10.15.3.192/27 | 11111111.11111111.11111111.11100000 | 32 | 10.15.3.193 | 10.15.3.222 | 10.15.3.223 | 255.255.255.224 |
10.15.3.224/27 | 11111111.11111111.11111111.11100000 | 32 | 10.15.3.225 | 10.15.3.254 | 10.15.3.255 | 255.255.255.224 |
Completed network assignments
Subnet Name | Needed Size | Allocated Size | Address | Mask | Dec Mask | Assignable Range | Broadcast |
---|---|---|---|---|---|---|---|
Guest | 500 | 510 | 10.15.0.0 | /23 | 255.255.254.0 | 10.15.0.1 – 10.15.1.254 | 10.15.1.255 |
Saes | 200 | 254 | 10.15.2.0 | /24 | 255.255.255.0 | 10.15.2.1 – 10.15.2.254 | 10.15.2.255 |
Engineering | 100 | 126 | 10.15.3.0 | /25 | 255.255.255.128 | 10.15.3.1 – 10.15.3.126 | 10.15.3.127 |
Finance | 50 | 62 | 10.15.3.128 | /26 | 255.255.255.192 | 10.15.3.129 – 10.15.3.190 | 10.15.3.191 |
Future use | 15 | 30 | 10.15.3.192 | /27 | 255.255.255.224 | 10.15.3.193 – 10.15.3.222 | 10.15.3.223 |
Future use | 15 | 30 | 10.15.3.224 | /27 | 255.255.255.224 | 10.15.3.225 – 10.15.3.254 | 10.15.3.255 |