1. What is a Subnet Mask?

A subnet mask is a 32-bit number that masks an IP address and divides it into network and host portions. It's used to determine which part of an IP address belongs to the network and which part belongs to the host.

2. How Does the Calculator Work?

The calculator uses the subnet mask formula:

Where:

• \( n \) — Number of bits in the network portion (CIDR notation)
• The formula calculates the last octet of a /24 to /32 subnet mask

Explanation: The formula calculates the value of the last octet in the subnet mask by determining how many host bits are available (8-n) and then creating the appropriate mask.

3. Importance of Subnet Masks

Details: Subnet masks are essential for proper network communication, allowing routers to determine whether to send packets to another network or keep them local. They help with network segmentation, security, and efficient IP address allocation.

4. Using the Calculator

Tips: Enter the number of bits in CIDR notation (0-32). The calculator will determine the corresponding subnet mask in dotted decimal notation.

5. Frequently Asked Questions (FAQ)

Q1: What is CIDR notation?
A: CIDR (Classless Inter-Domain Routing) notation represents an IP address and its network prefix in the format like 192.168.1.0/24, where /24 indicates 24 network bits.

Q2: What are common subnet masks?
A: Common ones include 255.0.0.0 (/8), 255.255.0.0 (/16), and 255.255.255.0 (/24).

Q3: Why do we need different subnet masks?
A: Different subnet masks allow for flexible network sizes, from very large (/8) to very small (/30) networks, optimizing IP address usage.

Q4: How does subnetting help with security?
A: Subnetting creates broadcast domains that limit traffic and can isolate network segments, improving security and performance.

Q5: What's the difference between subnet mask and wildcard mask?
A: A wildcard mask is the inverse of a subnet mask, used in access control lists (ACLs) to match specific IP addresses.