Subnet Overlap Checker
Instantly scan a list of IPv4 networks to detect IP address conflicts. Ensure your subnets are completely isolated before configuring VPC peering, VPNs, or complex routing.
Overlap Checker
Networks to Analyze
Example Input (Contains Overlaps):
10.0.0.0/16
10.0.5.0/24
192.168.1.0/24
192.168.1.128/25
10.0.5.0/24
192.168.1.0/24
192.168.1.128/25
Enter ≥ 2 valid networks in CIDR notation
Overlap Analysis Results
Detected Overlaps
| Conflict # | Network A | Overlaps With | Network B |
|---|
Analyzed Networks Details
| Network | Start IP (Network) | End IP (Broadcast) | Total IPs |
|---|
How to Use the Subnet Overlap Checker
This tool cross-references an entire list of networks against each other to find any intersections or conflicts. It is an essential step before linking branch offices, configuring VPC peering, or setting up VPNs.
- Enter your Networks: Type or paste your subnets in standard CIDR notation into the text area. You must place exactly one network per line (e.g.,
10.0.0.0/16). - Check Overlaps: Click the "Check Overlaps" button. The algorithm will calculate the absolute Start IP and End IP of every subnet and compare them against all other entries.
- Review Status: A green banner indicates your routing plan is safe. A red banner means you have collisions.
- Analyze the Conflicts: If overlaps are found, the "Detected Overlaps" table will list exactly which subnet is colliding with which, allowing you to quickly isolate and fix the problematic routes.
Example Overlap
If you input 10.0.0.0/16 and 10.0.5.0/24, the tool will instantly flag a conflict because the smaller /24 network is physically nested inside the larger /16 network boundary:
| Conflict # | Network A | Overlaps With | Network B |
|---|---|---|---|
| 1 | 10.0.0.0/16 | < Overlaps > | 10.0.5.0/24 |