CIDR notation, subnet masks, and the conversion table
Convert IPv4 CIDR prefixes to contiguous subnet masks and back, then check common masks, block sizes, and exact network boundaries.
Read guideUnderstand IPv4 boundaries
CIDR, subnet masks, host ranges, and private space
Three focused guides explain how a prefix creates a mask, how ordinary and special host boundaries differ, and exactly what RFC 1918 private space means.
Network, broadcast, and usable hosts—with /31 and /32
Understand the ordinary IPv4 host formula and why RFC 3021 /31 point-to-point links and /32 host routes need explicit rules.
Read guidePrivate IPv4 ranges: what RFC 1918 says—and does not say
Review the three RFC 1918 private blocks and avoid confusing private addressing with every special-purpose IPv4 range or with security.
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