Dhcpcd

Dynamic Host Configuration Protocol Client Daemon (dhcpcd) is a popular DHCP client for Gentoo Linux users.

Emerge
Use the following command to install dhcpcd:

Files
All configuration can be set in the  file, but for most installations  will work out of the box presuming most computers nowadays are behind a router or access point providing DHCP. Though will be helpful in case advanced configuration is required.

Network management with netifrc scripts
can be used with or without Gentoo's netifrc scripts.

Network management with netifrc scripts
When netifrc scripts are being used as the primary method to control network interfaces can be used as the DHCP client. All that is necessary for operation is that each interface be set to  in. See the Network configuration section of the Gentoo Handbook for more information.

In this configuration will conflict with netifrc scripts if added to a run level. Verify it has been removed:

Static IP addresses
In case the network interface card should be configured with a static IP address, add their data to. The following is an example of manually adding a static address, routes, and DNS by editing DHCPCD's configuration file using a text editor of choice:

One-time DHCP
To configure a network interface for one-time DHCP use issue the following command:

Be sure to replace  in the command above with the appropriate network interface name.

External resources

 * Dhcpcd on the Arch Wiki