Subnet Containment Checker

Check if an IP address is contained within a subnet

What is Subnet Containment?

Subnet containment determines whether an IP address belongs to a specific subnet. This tool checks if an IP address falls within the range defined by a subnet's network address and subnet mask. It supports both IPv4 and IPv6 addresses with CIDR notation and provides a visual breakdown of the binary logic used in the calculation.

IP Address

Enter the IP address to check

Subnet (CIDR)

Enter subnet with CIDR notation

Understanding Subnet Containment

How does subnet containment work?

Binary AND operation: To check if an IP is in a subnet, we perform a bitwise AND operation between the IP address and the subnet mask, then compare the result with the network address.

Example: IP 192.168.1.100 in subnet 192.168.1.0/24

Logic: (IP & Mask) == Network Address

IPv4 vs IPv6

IPv4: 32-bit addresses with dotted decimal notation (e.g., 192.168.1.1)

IPv6: 128-bit addresses with hexadecimal notation (e.g., 2001:db8::1)

CIDR: Both use CIDR notation (/24 for IPv4, /64 for IPv6)

Common subnet examples

IPv4 subnets:

/24: 192.168.1.0/24 (256 addresses)
/16: 10.0.0.0/16 (65,536 addresses)
/8: 172.16.0.0/8 (16.7M addresses)

IPv6 subnets:

/64: 2001:db8::/64 (standard subnet)
/48: 2001:db8::/48 (site prefix)

Practical applications

Network administration: