Subnet Overlap
Paste a list of CIDR networks (IPv4 or IPv6, one per line) and find out which pairs overlap or whether one network contains another, and check whether a single IP falls inside any of them. Nothing is sent to any server.
IP membership
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Conflicting pairs
0| Network A | Relation | Network B | Detail |
|---|
No pair overlaps or contains another: the networks are disjoint.
Range of each network
| Network | Family | Start | End | Addresses | Status |
|---|
How it is calculated · overlap and containment
1. Each CIDR is turned into an integer range
[start, end]. IPv4 uses a 32-bit unsigned
integer; IPv6 a 128-bit one (with BigInt).
2. start = ip & mask and
end = start + 2^(bits − prefix) − 1, where
bits is 32 (IPv4) or 128 (IPv6).
3. Two networks overlap if
start₁ ≤ end₂ && start₂ ≤ end₁.
4. There is containment (one ⊆
the other) if start_a ≤ start_b && end_b ≤ end_a.
Only networks of the same family are compared (IPv4 with IPv4, IPv6 with IPv6).
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