The inventory_hostname magic variable will return the hostname of a manage node as listed in your default hosts file or your own inventory file. The ansible_hostname magic variable will return the hostname of a managed node (e.g. the target system), just like the Linux hostname command. Or, the following can be used to invoke this module on the control node (that's your Ansible server). 

• local_action module
• delegate_to parameter
• connection parameter
• hostvars magic variable

For example, let's say you have the following playbook. 

---
- hosts: all
  tasks:
    - debug
        msg: Ansible hostname is {{ ansible_hostname }}

    - debug
        msg: Inventory hostname is {{ inventory_hostname }}

    - debug
        msg: Short inventory hostname is {{ inventory_hostname_short }}

Running this playbook could return something like this.

TASK [debug]
ok: [server1.example.com] => {
    "msg: "Ansible hostname is server1"
}

TASK [debug]
ok: [server1.example.com] => {
    "msg: "Inventory hostname is server1.example.com"
}

TASK [debug]
ok: [server1.example.com] => {
    "msg: "Short inventory hostname is server1"
}