Equal Division of Network Address 172.20.10.0/23 into Four Subnets: A Step-by-Step Guide

When managing network infrastructure, it is crucial to efficiently allocate IP addresses to different segments, known as subnets. This article provides a detailed walkthrough of how to divide the network address 172.20.10.0/23 into four equal subnets. The tutorial includes steps to determine the new subnet mask, the number of addresses within each subnet, and the allocation of specific IP addresses such as the network address, first usable IP address, last usable IP address, and broadcast IP address.

Step 1: Determine the New Subnet Mask

The original network address is 172.20.10.0/23. This notation means that there are 23 bits allocated to the network segment and 9 bits for individual hosts. The /23 subnet mask translates to 255.255.255.0, providing 2^9 or 512 total addresses, but only 510 usable addresses after subtracting 2 for the network and broadcast addresses.

To divide this address into four equal subnets, we need to borrow 2 bits from the host portion, increasing the subnet mask to /25, which corresponds to 255.255.255.128. This will increase the network address range to 2^7 or 128 total addresses per subnet, providing 126 usable addresses after the same removal of 2 addresses for network and broadcast.

Step 2: Calculate the Number of Addresses

For each of the four subnets with a /25 subnet mask, the number of addresses can be calculated as follows:

Network addresses: 172.20.10.0, 172.20.10.128, 172.20.11.0, 172.20.11.128 Subnet mask: 255.255.255.128 First usable IP address: Subtract 1 from the network address (172.20.10.1, 172.20.10.129, 172.20.11.1, 172.20.11.129) Last usable IP address: The maximum IP address minus 1 (172.20.10.126, 172.20.10.254, 172.20.11.126, 172.20.11.254) Broadcast IP address: The maximum IP address (172.20.10.127, 172.20.10.255, 172.20.11.127, 172.20.11.255)

Step 3: Identify Each Subnet

The division of the original network address into four subnets yields the following detailed information for each subnet:

Subnet 1

Network Address: 172.20.10.0 Subnet Mask: 255.255.255.128 First Usable IP Address: 172.20.10.1 Last Usable IP Address: 172.20.10.126 Broadcast IP Address: 172.20.10.127

Subnet 2

Network Address: 172.20.10.128 Subnet Mask: 255.255.255.128 First Usable IP Address: 172.20.10.129 Last Usable IP Address: 172.20.10.254 Broadcast IP Address: 172.20.10.255

Subnet 3

Network Address: 172.20.11.0 Subnet Mask: 255.255.255.128 First Usable IP Address: 172.20.11.1 Last Usable IP Address: 172.20.11.126 Broadcast IP Address: 172.20.11.127

Subnet 4

Network Address: 172.20.11.128 Subnet Mask: 255.255.255.128 First Usable IP Address: 172.20.11.129 Last Usable IP Address: 172.20.11.254 Broadcast IP Address: 172.20.11.255

Summary of Each Subnet

SubnetNetwork AddressSubnet MaskFirst Usable IPLast Usable IPBroadcast IP Subnet 1172.20.10.0255.255.255.128172.20.10.1172.20.10.126172.20.10.127 Subnet 2172.20.10.128255.255.255.128172.20.10.129172.20.10.254172.20.10.255 Subnet 3172.20.11.0255.255.255.128172.20.11.1172.20.11.126172.20.11.127 Subnet 4172.20.11.128255.255.255.128172.20.11.129172.20.11.254172.20.11.255

Conclusion

By dividing the network address 172.20.10.0/23 into four equal subnets, we achieve an efficient and manageable allocation of IP addresses, ensuring clear separations between each segment without wasting valuable IP resources. This approach is widely applicable in enterprise networks, data centers, and other extensive network infrastructures.