PebbleRack

Guide 04 of 25 · beginner

Plan addresses and names without disrupting your network

Use the existing router's DHCP service and record a stable way to find your lab host.

Source-verified · Not lab-testedOfficial sources checked 2026-09-29. No PebbleRack hardware compatibility claim.

Outcome

The lab host will have a planned hostname and a documented way to receive an address. You will know who controls DHCP and DNS before changing either one.

Before you start

Use the private map from guide 02 and have administrator access to your own router if you intend to make a reservation. Keep a local screen and keyboard available while changing network settings. This guide assumes a normal home network with one existing DHCP server; it does not require new router firmware, VLANs, or a public domain.

Steps

  1. Choose a descriptive hostname. Use a short name such as lab-host rather than a product or role that might change. Check the router's client list for collisions. Record the name in your private inventory.
  2. Find the DHCP server. On your router, identify the address pool and existing reservations. Do not add a second DHCP server to the same network just to give the lab host a stable address. That can make clients receive inconsistent gateways or DNS servers.
  3. Start with DHCP. During installation, let the router assign an address. Canonical's installer uses DHCP for a wired interface when available. After boot, use ip address, ip route, and resolvectl status to see the actual address, default route, and DNS servers. Record what you observe rather than guessing.
  4. Add a reservation if stability is needed. In the router interface, reserve an address for the host's network interface using the router's supported workflow. Pick an address that the router permits for reservations and is not already assigned. Record the old and new settings. Reconnect or renew the host connection, then confirm the assigned address matches the reservation. Router menus and behavior vary, so follow its manual.
  5. Plan names separately from addresses. If the router advertises local hostnames, test resolution from a second client. If it does not, use the address from the private inventory for the first service. Do not invent a public DNS record or change pebblerack.com for a private lab. Avoid editing /etc/resolv.conf directly on an Ubuntu system managed by systemd-resolved.
  6. Record the fallback. Write down how to access the router locally, remove the reservation, and reach the host by screen and keyboard. Do not switch a remote-only host from DHCP to a static Netplan configuration without an out-of-band recovery path. Ubuntu provides Netplan for static configuration, but that is a later, deliberate change.

Check it worked

The host gets an address after restart, has a default route, and resolves a known public domain. A second client can reach it by the chosen name if local DNS was configured, or by its recorded address. Test from the actual client you will use.

If it fails / rollback

If the host loses connectivity after a reservation, remove or correct the reservation in the router and renew the host lease or reboot. If DNS alone fails, inspect resolvectl status and restore the router's prior DNS settings. Use local console access while diagnosing.

Safety and data notes

Do not expose router screenshots, internal addresses, MAC addresses, or administration credentials in public help posts. Keep the household's existing network working; do not replace its gateway or DNS service during this beginner path.

Sources

Next guide

Continue to guide 05, “Install Ubuntu Server LTS.”