What is the maximum number of hosts that can be processed simultaneously in Ansible by default when running playbooks?

By default, Ansible runs tasks in parallel on 5 hosts simultaneously. This value is set by the forks parameter in the ansible.cfg configuration file.

If you need to increase the number of hosts processed simultaneously, you can change this parameter, for example:

[defaults]
forks = 20

Thus, by default, Ansible processes up to 5 hosts in parallel.