Question

Now that you have gained some expertise in creating addressing schemes, demonstrate how you would divide the IPv4 network address of 201.100.50.0/24 such that each subnet would support 40 hosts. What subnet mask would you need? What is the range of addresses for the first subnet? (15 points)

Answer 1

To divide the IPv4 network address of 201.100.50.0/24 so that each subnet can support 40 hosts, we first need to determine the required subnet size.

### Step 1: Determine the Number of Bits Required for Hosts

The formula to determine the number of host addresses that can be supported by a subnet is:

\[
2^h - 2 \geq \text{{number of hosts needed}}
\]

where \( h \) is the number of host bits. The "-2" accounts for the network and broadcast addresses.

For 40 hosts:

\[
2^h - 2 \geq 40
\]

Calculating the powers of 2:

- \( 2^5 - 2 = 32 - 2 = 30 \) (not enough)
- \( 2^6 - 2 = 64 - 2 = 62 \) (sufficient)

Thus, we need at least 6 bits for the host addresses.

### Step 2: Calculate the New Subnet Mask

The original subnet mask for 201.100.50.0/24 is 255.255.255.0. In CIDR notation, this is a /24 prefix, which means there are 32 - 24 = 8 bits available for hosts.

Since we need 6 bits for host addresses, we can use:

\[
8 - 6 = 2 \text{ bits for subnetting}
\]

This means the new subnet mask will use 24 + 2 = 26 bits for the network. Therefore, the new subnet mask in CIDR notation is \(/26\).

### Step 3: Calculate the Number of Subnets

Using 2 bits for subnetting, the number of possible subnets is:

\[
2^2 = 4 \text{ subnets}
\]

### Step 4: Determine the Address Range for the First Subnet

With a /26 subnet mask (255.255.255.192), we can calculate the subnets. Each subnet will have \(2^6 = 64\) addresses (including network and broadcast addresses):

1. **First subnet**:
- Network Address: 201.100.50.0
- First usable address: 201.100.50.1
- Last usable address: 201.100.50.62
- Broadcast Address: 201.100.50.63

### Summary

- **Subnet Mask**: 255.255.255.192 (or /26)
- **Range of Addresses for the First Subnet**:
- Network Address: 201.100.50.0
- First Usable Address: 201.100.50.1
- Last Usable Address: 201.100.50.62
- Broadcast Address: 201.100.50.63

This configuration allows for 4 subnets, each capable of supporting 40 hosts.