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CIDR to Subnet Mask

Convert prefix length to dotted-decimal mask plus wildcard.

Subnet mask255.255.255.0
Wildcard0.0.0.255

How to read the result

Prefix N = N one-bits then zeros. /24 = 24 ones = 255.255.255.0.

Example

/24 → 255.255.255.0

FAQ

Common values?

/8=255.0.0.0, /16=255.255.0.0, /24=255.255.255.0.