Which file format is commonly used for network configuration in modern Ubuntu systems?

The common file format used for network configuration in modern Ubuntu systems is YAML. This format is favored because it is user-friendly and allows for a clear and hierarchical representation of configuration data. With the introduction of Netplan in Ubuntu, which is utilized for managing network configurations in newer versions, YAML files are now the standard way to define network settings.

YAML’s simplicity makes it easier for both humans and machines to read and write the configuration. It uses indentation to represent structure, which helps in organizing complex configurations without the need for excessive punctuation or symbols, as seen in other formats.

While other formats like .conf, .cfg, and .json can also be used in different contexts or applications, they are not the standard for Ubuntu's network configurations. The .conf files are generally associated with more traditional services, .cfg could be considered somewhat generic, and .json, while effective for data interchange, lacks the straightforward readability and structure that YAML provides in the context of managing network settings.