How should I configure additional IPs or a routed subnet on a dedicated server?
Additional addresses may be delivered as on-link IPs, routed subnets, failover IPs or provider-specific virtual-MAC arrangements. Those models are not interchangeable. Obtain the exact assigned addresses, prefix lengths, gateway and routing requirements before writing a network profile; guessing a /24 or copying the primary gateway can break connectivity.
Before you start
- Authorised access to the dedicated server and the named inspection tools.
Instructions
1. Inspect the current address and route state
Record the interface layers and route table that currently provide management access. Include IPv6 separately if it is part of the service.
ip -br address
ip -4 route show
ip -6 route showCompare the output with the provider’s assigned network plan. Do not publish unrelated tenant addresses in a support example.
2. Check the route chosen for an intended destination
A route lookup is read-only and does not transmit the application traffic itself. Replace the documentation address with the approved destination used for verification.
ip route get 198.51.100.20The chosen source address and interface help identify whether the intended additional address needs policy routing, an on-link route or another provider-supported design.
Check the result
- The approved configuration preserves the original management route and makes each assigned address reachable in the required direction, with source-address behaviour verified.
Troubleshooting
- An added IP is unreachable despite being listed
- Check provider assignment, ARP/ND rules, routed-subnet model, virtual-MAC requirements and local firewall policy.
- Replies leave through the wrong source or interface
- Review policy routing and the supported address model instead of adding arbitrary default routes.
Official references
Use the documentation for your installed version when a flag, service name or platform feature differs.