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Difficulty: MediumIPv4 Addressing and Subnetting

A network engineer is provisioning a dedicated IP address pool for an automated distribution center's IoT sensor array using the IPv4 network block 172.24.16.0/23172.24.16.0/23. How many usable IPv4 host addresses are available for assignment to end devices within this subnet?

Answer: 510 addresses

Answer

The subnet provides 510 usable IPv4 host addresses.
A /23 subnet mask leaves 9 host bits (32−23=932 - 23 = 9). The total number of IP addresses is 29=5122^9 = 512. Subtracting 2 for the unassignable network and broadcast addresses yields 510 usable host IP addresses.

Step-by-Step Solution

1
Determine the number of host bits available in a /23 prefix.
32 total bits - 23 network bits = 9 host bits.
An IPv4 address consists of 32 bits, divided between network prefix bits and host bits.
2
Calculate total IP address space for 9 host bits.
2^9 = 512 total IP addresses.
Binary exponentiation gives the total number of unique bit combinations.
3
Subtract reserved addresses to get usable host count.
512 - 2 = 510 usable host addresses.
The first IP address (network identifier) and last IP address (directed broadcast) cannot be assigned to hosts.

Key Concept

IPv4 Usable Host Calculation
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Topics

IPv4 Addressing and Subnetting

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