Don’t put your server on DHCP, I mean keep it with the same static IP when Oracle was installed (if you change Server’s IP, manually or dynamically, oracle will have to be reinstalled). Rest all machines except the servers can be put on DHCP.
A change in IP does not require a new installation of the Oracle database software. I have moved servers to new subnets within a DNS domain numerous times. If your tnsnames entry identifies the database using Hostname with a fully qualified domain, then no changes will be required. If your tnsnames.ora entry uses the IP addresses to identify the host, then any change in IP will need to be reflected in the tnsnames.ora entry. For a database server, a static IP address should be required, but as long as the hostname is fully qualified and both the nslookup and reverse lookup work properly and point to the same host, you should be able to communicate.