Troubleshooting

5 MIN READ

Apr 19, 2026

Commands for Checking Routing Tables

Inspect Linux FIB entries with ip route, unravel policy routing via ip rule, read Windows metrics with route print and Get-NetRoute, and document VPN split tunnels before you change default gateways.

Linux main table

ip route (short for ip route show table main) prints the active forwarding table: default via gateway, more-specific prefixes, and on-link subnets. Use ip -4 route or ip -6 route when dual-stack noise obscures IPv4.

Policy routing

Corporate VPNs and multi-WAN setups add routing rules that select alternate tables based on source address, fwmark, or uid. Run ip rule list then ip route show table <name> for each non-main table. ip route get 203.0.113.5 from 192.0.2.10 shows which path the kernel would choose for a given tuple.

Windows

route print remains the quick ASCII view. PowerShell Get-NetRoute -AddressFamily IPv4 | Sort-Object RouteMetric highlights overlapping routes—lower metric wins for equal prefix length.

BGP and the internet

Host routing tables show your next hop, not the full internet. For provider-specific AS paths use a public looking glass after you confirm local defaults are sane.

Frequently Asked Questions

Q.Why does my laptop still use the old default route after VPN disconnect?

Stale interface metrics or persistent routes remain—flush VPN interfaces, restart the tunnel client, or remove static routes the VPN added. Compare ip route before and after connect.

Q.What does ip route show table all display?

Every configured table the kernel knows about, not only those actively selected. Pair with ip rule to see which table applies to a given packet.

Q.How do I see which interface traffic to a host would use?

Run `ip route get A.B.C.D` on Linux. On Windows use `Find-NetRoute -RemoteIPAddress A.B.C.D` (PowerShell) to reveal the chosen interface and next hop.

Q.Why are there two default routes with different metrics?

Failover or policy design—Wi-Fi vs Ethernet, or wired primary with cellular backup. Ensure intentional ordering; accidental equal-cost paths can cause asymmetric flows.

Q.Does traceroute replace reading the routing table?

No—traceroute shows path on the wire for one flow; routing tables show local forwarding decisions. Misconfigured policy routing can still produce surprising traceroute hops.

Q.How does split tunneling appear in ip rule?

You may see rules pushing corporate prefixes into a VPN table while default stays on the physical uplink. Document those rules before editing server-side split lists.

Q.Why does IPv6 use a different default than IPv4?

Separate RAs and DHCPv6 options install distinct ::/0 routes. Check `ip -6 route` and router advertisements when only one family breaks.

Q.Can I safely delete a route I do not recognize?

Only after you confirm it is not required for management access or out-of-band networks. Prefer toggling the owning service (VPN, SD-WAN agent) over manual `ip route del` on production nodes.

TOPICS & TAGS

ip route showip rule listLinux policy routingroute print WindowsGet-NetRoute