Reading the Windows routing table without guessing
Every packet your PC sends is matched against the Windows routing table. The command-line output from route print lists the entries, but it leaves the hard part to you: working out which of several overlapping routes wins for one particular address, especially once a VPN or a second adapter adds its own.
Routing Table Manager answers that directly. Type an IP address or a host name into the box at the top and the app writes the address out in binary, lines each candidate route up underneath it, and highlights the winner. A route that does not match shows the exact bit where it diverges. A single sentence states the reason, whether a longer prefix won or two equal prefixes were split by metric, and the winning row is marked in the table below.
The comparison follows the rules Windows uses: longest prefix match first, then the lowest total metric, which is the route metric plus the interface metric.
How to add a static route in Windows that survives a restart
Each field is checked as you go, so a malformed address or mask is flagged on that field before anything is sent. Persistent routes show a pin in the Kept after restart column, which makes it easy to spot leftovers from an old project.
- Click Add route.
- Choose the Interface the traffic should leave by.
- Enter the Destination network, for example 10.20.0.0.
- Under Mask or prefix length, type either a dotted mask such as 255.255.0.0 or just 16.
- Fill in Gateway with the next-hop router, or leave it empty for an on-link route.
- Set the Metric. It starts at 300; lower numbers are preferred when prefixes tie.
- Tick Keep after restart for a persistent route, then press Add and accept the Windows permission prompt.
Delete a route, or check that its gateway answers
Select a row and press Delete to remove it; Windows asks for permission for that one change and nothing else. Ping gateway sends a quick check to an IPv4 next hop, which settles whether a route is broken or merely unused. Right-click any row to copy its destination or gateway, or to hide it until the next refresh.
Longest prefix match, route metric and the VPN problem
Longest prefix match means the most specific route wins. A /24 route for 192.168.5.0 beats the 0.0.0.0/0 default route for 192.168.5.40, however low the default's metric is. Only when two routes are equally specific does the metric decide.
That is how many VPNs take over all traffic. Some install a default route with a lower metric than your Wi-Fi; others add two /1 routes that are more specific than any default. When the app sees either, it shows a warning naming the VPN adapter, which explains why a printer or file share on your home network has gone unreachable. Type the device's address into the tester to see which route is winning.
