# http://docs.ansible.com/ansible/intro_inventory.html

[all:vars]
#host_key_checking=false
ansible_ssh_common_args='-o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no'
#information_environment=dev
#information_product=prod1
#ansible_ssh_user=ubuntu
#ansible_ssh_pass=pass1234
#ansible_user=root

[example.com]
www.example.com
db.example.com



[all:children]
local
example.com

[local:children]
phy.local
vm.local

[phy:children]
phy.local
phy.example.com

[phy.local]
www.local
db.local
backup.local
lxc.local ansible_host=192.168.1.11

Order hosts in playbook
https://docs.ansible.com/ansible/latest/user_guide/playbooks_intro.html#hosts-and-users
inventory: The default. The order is ‘as provided’ by the inventory
reverse_inventory: As the name implies, this reverses the order ‘as provided’ by the inventory
sorted: Hosts are alphabetically sorted by name
reverse_sorted: Hosts are sorted by name in reverse alphabetical order
shuffle: Hosts are randomly ordered each run

# Ansible 2.2
- hosts: "{{ ansible_play_hosts | sort() }}"

# Ansible >2.4
- hosts: all
  order: sorted
  tasks:
    - debug:
        var: inventory_hostname

Links
https://docs.ansible.com/ansible/2.4/intro_configuration.html#inventory