Subnet Calculator
Calculate subnet masks, network addresses, and IP ranges.
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Essential Tool for Network Planning
An essential tool for network administrators and IT students. Our Subnet Calculator takes an IP address and a CIDR notation (e.g., /24) to calculate the network address, broadcast address, the total number of hosts, and the range of usable IP addresses within that subnet. It simplifies the complex task of IP subnetting.
The Formulas Explained
subnetting involves binary math and bitwise operations:
- Subnet Mask: A 32-bit number where the first 'n' bits (from the CIDR) are 1s and the rest are 0s.
- Network Address: The result of a bitwise
ANDoperation between the IP address and the subnet mask. - Broadcast Address: The result of a bitwise
ORoperation between the Network Address and the inverse of the subnet mask. - Host Range: The range of addresses between the Network Address and the Broadcast Address (excluding those two addresses).
How to Use the Calculator
- IP Address: Enter a valid IPv4 address (e.g.,
192.168.1.100). - Subnet Mask (CIDR): Enter the CIDR notation (the number after the
/, e.g.,24). - Calculate: The tool will display the key information for that subnet.
Real-World Example
You have the IP address 192.168.1.100 with a subnet mask of /24.
- IP Address: 192.168.1.100
- Subnet Mask: 255.255.255.0 (which is /24)
- Network Address: 192.168.1.0
- Broadcast Address: 192.168.1.255
- Number of Usable Hosts: 254 (2⁸ - 2)
- Usable IP Range: 192.168.1.1 to 192.168.1.254
Frequently Asked Questions (FAQ)
- What is CIDR? Classless Inter-Domain Routing (CIDR) is a method for allocating IP addresses and IP routing. The CIDR notation (e.g., /24) is a shorthand way of representing a subnet mask.
- Why are two addresses unusable? In any given subnet, the first address is reserved as the network address (to identify the network itself) and the last address is reserved as the broadcast address (to send messages to all devices on the network). Therefore, they cannot be assigned to individual hosts.
- What is this used for? Subnetting is used to divide a large network into smaller, more manageable sub-networks. This improves performance, simplifies management, and enhances security.