Subnetting - How to determine the number of subnets and the number of hosts per
subnet?
Problem 1
IP Address 198.165.32.36/28
Answer the following questions by following all necessary steps.
Address class ________________________
The first/Network address ________________________
Custom subnet mask ________________________
Total number of subnets ________________________
Total number of host addresses ________________________
Number of usable addresses ________________________
Number of bits borrowed ________________________
What is the 2 nd subnet range? ______________________
What is the subnet number for the 5th subnet? ______________________
What is the subnet broadcast address for the 7th subnet? ______________________
Assignable addresses range for the 6th subnet? _____________________
To determine the number of subnets and the number of hosts per subnet, follow these steps:
1. Identify the address class:
- The given IP address, 198.165.32.36/28, belongs to Class C because the first octet is between 192 and 223.
2. Calculate the number of bits borrowed for subnetting:
- The /28 CIDR notation indicates that 28 bits are used for the network portion and the remaining 4 bits are used for the host portion.
3. Calculate the total number of subnets:
- The formula to calculate the number of subnets is 2^b (where b is the number of bits borrowed for subnetting).
- In this case, 2^4 = 16 subnets.
4. Calculate the total number of host addresses:
- The formula to calculate the total number of host addresses is 2^h - 2 (where h is the number of host bits).
- In this case, 2^4 - 2 = 14 host addresses per subnet.
5. Calculate the number of usable addresses:
- Since the first and last address in each subnet are reserved for the network and broadcast addresses, the number of usable addresses is the total number of host addresses minus 2.
- In this case, 14 - 2 = 12 usable addresses per subnet.
6. Determine the number of bits borrowed:
- The number of bits borrowed for subnetting is given as 4.
7. Determine the second subnet range:
- To calculate the second subnet range, multiply the number of subnets by the number of host addresses per subnet.
- In this case, the second subnet range would be from 198.165.32.48 to 198.165.32.63.
8. Determine the subnet number for the fifth subnet:
- To calculate the subnet number for the fifth subnet, multiply the subnet range (number of subnets) by the number of host addresses per subnet, and then add the subnet range of the first subnet.
- In this case, the subnet number for the fifth subnet would be 198.165.32.80.
9. Determine the subnet broadcast address for the seventh subnet:
- To calculate the subnet broadcast address for the seventh subnet, add the host addresses per subnet to the subnet range of the seventh subnet.
- In this case, the subnet broadcast address for the seventh subnet would be 198.165.32.111.
10. Determine the assignable addresses range for the sixth subnet:
- To calculate the assignable addresses range for the sixth subnet, add 1 to the subnet range of the sixth subnet as the starting address, and subtract 1 from the subnet broadcast address as the ending address.
- In this case, the assignable addresses range for the sixth subnet would be from 198.165.32.64 to 198.165.32.79.