How many usable hosts are available in a subnet with a /28 prefix?

Practice Questions

Q1
How many usable hosts are available in a subnet with a /28 prefix?
  1. 14
  2. 16
  3. 30
  4. 32

Questions & Step-by-Step Solutions

How many usable hosts are available in a subnet with a /28 prefix?
  • Step 1: Understand what a /28 prefix means. A /28 prefix indicates that the first 28 bits of the IP address are used for the network part, and the remaining bits are used for host addresses.
  • Step 2: Calculate the total number of addresses in a /28 subnet. A /28 subnet has 32 - 28 = 4 bits left for host addresses. The total number of addresses is 2 raised to the power of the number of host bits: 2^4 = 16.
  • Step 3: Identify the reserved addresses. In every subnet, 1 address is reserved for the network address and 1 address is reserved for the broadcast address.
  • Step 4: Subtract the reserved addresses from the total addresses. So, 16 total addresses - 2 reserved addresses = 14 usable host addresses.
  • Subnetting – Understanding how to calculate the number of usable hosts in a subnet based on the CIDR notation.
  • CIDR Notation – Knowledge of how the prefix length (e.g., /28) affects the total number of addresses in a subnet.
  • Reserved Addresses – Recognizing that the first address is the network address and the last address is the broadcast address, which cannot be assigned to hosts.
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