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Overlap Checker

Two-CIDR checker

On the VLSM tab, the Subnet Overlap Checker panel accepts two CIDRs (IPv4 or IPv6). Possible results:

Result Meaning
No overlap The ranges are completely disjoint
Identical subnets Both CIDRs are the same block
A contains B The first CIDR fully contains the second
B contains A The second CIDR fully contains the first
Overlap The ranges partially intersect

Multi-CIDR checker

The Multi-CIDR Overlap Check panel accepts up to 50 CIDRs (one per line, IPv4 or IPv6 mixed). It reports all conflicting pairs with their relationship.

If no overlaps are detected, a "No overlaps detected" message is shown.

Tip

Use the multi-CIDR checker to audit an existing address plan before deploying.