Which protocol is used when a host connects to a new network an IP address dynamically?

DHCP -Dynamic Host Configuration Protocol

this protocol make network devices to discover its IP address, mask, and default gateway

Dynamic Host Configuration Protocol DHCP

dhcp protocol 

The Dynamic Host Configuration Protocol (DHCP) is a standardized network protocol used on Internet Protocol (IP) networks for dynamically distributing network configuration parameters, such as IP addresses for interfaces and services. With DHCP, computers request IP addresses and networking parameters automatically from a DHCP server, reducing the need for a network administrator or a user to configure these settings manually.