Default Gateway Calculator
Determine the likely default gateway IP address for any network given an IP address and subnet mask or CIDR notation.
Understanding Default Gateways
A default gateway is the node in a computer network that serves as the forwarding host to other networks when no other route specification matches the destination IP address.
Key Concepts
| Term | Description | Example (192.168.1.0/24) |
|---|---|---|
| Default Gateway | Router interface IP on the local network | 192.168.1.1 |
| Common Positions | Typical gateway IP locations | .1 (first) or .254 (last) |
| Routing Table | Contains gateway information | 0.0.0.0 → 192.168.1.1 |
Common Default Gateway Positions
| Network Type | Common Gateway IP | Example |
|---|---|---|
| Home/Small Office | First usable IP | 192.168.1.1 |
| Enterprise Networks | Last usable IP | 192.168.1.254 |
| Point-to-Point | Either end | 192.168.1.1 or 192.168.1.2 |
| Custom Configurations | Any usable IP | 192.168.1.100 |
Frequently Asked Questions
What is the most common default gateway IP?
In home and small office networks, the first usable IP (typically ending in .1) is most common. For example, in a 192.168.1.0/24 network, the gateway is often 192.168.1.1.
Can the default gateway be any IP in the subnet?
Yes, technically any usable host IP can be configured as the default gateway, though network administrators typically choose predictable positions (like .1 or .254) for consistency.
How do I find my current default gateway?
You can find your default gateway by:
- Windows: Run `ipconfig` in Command Prompt
- Mac/Linux: Run `netstat -rn` or `ip route` in Terminal
- Router Admin: Check your router's configuration page
What happens if I configure the wrong default gateway?
With an incorrect gateway:
- Local network communication will still work
- Access to other networks/internet will fail
- You may see "destination host unreachable" errors
Can a network have multiple default gateways?
Yes, but typically only one is active at a time for redundancy. Multiple gateways can be configured for failover scenarios.
How does the default gateway relate to DHCP?
DHCP servers typically provide the default gateway information along with IP address assignments. The gateway option (option 3) is part of the DHCP offer.
What's the difference between a default gateway and a router?
The default gateway is the IP address of the router interface on your local network, while the router is the physical device that performs the routing between networks.
How do I troubleshoot gateway connectivity issues?
Troubleshooting steps:
- Ping the gateway IP to check basic connectivity
- Verify correct IP and subnet mask on your device
- Check physical connections and link lights
- Verify router configuration
- Test with another device on the same network
Default Gateway Examples
| Network | Subnet Mask | Common Gateway |
|---|---|---|
| 192.168.1.0 | 255.255.255.0 | 192.168.1.1 |
| 10.0.0.0 | 255.0.0.0 | 10.0.0.1 |
| 172.16.5.0 | 255.255.255.252 | 172.16.5.1 |
| 192.168.10.0 | 255.255.255.128 | 192.168.10.1 |