A. Change hostname

$ hostnamectl set-hostname new-hostname

Check hostname

$ hostname

Reboot the server

B. Change IP Address

Find the following file – /etc/netplan/01-netcfg.yaml OR  50-cloud-init.yaml

Edit the IP/Interface info –

$ sudo chmod 600 /etc/netplan/01-netcfg.yaml
network:
  version: 2
  renderer: networkd
  ethernets:
    enp0s3:
      dhcp4: no
      addresses:
        - 192.168.1.10/24
      routes:
        - to: default
          via: 192.168.1.1
      nameservers:
        addresses: [8.8.8.8, 8.8.4.4]

Ensure that the Netplan configuration file permissions are secure to prevent unauthorized access.

$ sudo chmod 600 /etc/netplan/01-netcfg.yaml

Apply the configuration change

$ sudo netplan apply

Verify the ip address

$ ip a