linuxexpert-practice-labs/labs/lfcs/2-1-ip-and-name-resolution/README.md

LFCS 2.1: IPv4, IPv6 and name resolution

Static addresses, gateways and DNS servers for IPv4 and IPv6, a second address, the hostname, /etc/hosts, and a DNS search domain, all persistent.

Before you start

The lab notes the main interface's current address, gateway and DNS server in /root/lab-network.txt. Keep that address, gateway and DNS server in task 1 or 2 so the VM stays reachable; only the way they're set changes. Work from the console, not SSH, while you change the main interface, and take a snapshot first.

Tasks

1. RHEL family: give the main interface a static IPv4 address, gateway and DNS server (the ones in /root/lab-network.txt), plus the static IPv6 address 2001:db8:10::20/64 with gateway 2001:db8:10::1, all persistent, with NetworkManager.
2. Ubuntu: do the same with netplan.
3. Add a second IPv4 address, 192.0.2.21/24, to the main interface without removing the first, persistently.
4. Set the hostname to lab1.example.org, and make db1 resolve to 192.168.122.30 without DNS.
5. Add example.org as a DNS search domain, persistently, so that getent hosts www resolves www.example.org.

Hints

• nmcli connection modify with ipv4.method manual, ipv4.addresses, ipv4.gateway, ipv4.dns, and the same for ipv6; then nmcli connection up.
• On Ubuntu, cloud-init writes /etc/netplan/50-cloud-init.yaml: edit it (or override it in a file that sorts later), tell cloud-init to leave the network alone, then netplan try or netplan apply.
• +ipv4.addresses adds an address; in netplan, addresses: is a list.
• hostnamectl set-hostname, /etc/hosts, getent hosts.
• ipv4.dns-search, or search: under nameservers: in netplan.
• ip -br addr, ip route, ip -6 route, resolvectl status.