Step By Step Oracle 19C RAC Installation on Oracle Linux 7.9

Public IP:  The public IP address is for the server.  This is the same as any server IP address, a unique address with exists in /etc/hosts.

Private IP: Oracle RAC requires “private IP” addresses to manage the CRS, the clusterware heartbeat process and the cache fusion layer.

Virtual IP:  Oracle uses a Virtual IP (VIP) for database access.  The VIP must be on the same subnet as the public IP address.  The VIP is used for RAC failover (TAF). 

Networking Files:

The "/etc/sysconfig/network" file holds top-level networking configuration, including the hostname and gateway settings.

The "/etc/sysconfig/network-scripts/ifcfg-eth0" file holds the network configuration for the "eth0" adapter. If you have multiple network adapters, you would expect additional configuration files (eth1, eth2 etc.). The following example contains the configuration for a DHCP adapter.

The "/etc/hosts" file contains information for local name resolution.

The "/etc/resolv.conf" file is used to configure the location of the DNS servers to be used for name resolution. There can be multiple "nameserver" lines, one for each nameserver.

The "/etc/sysconfig/network-scripts" directory contains a number of network related scripts and commands. The ifdown and ifup commands are used to stop and start the specified network adapters.

The current network settings are displayed using the ifconfig command.

https://serhatcelik.wordpress.com/2021/02/15/step-by-step-oracle-19c-rac-installation-on-oracle-linux-7-9/

https://serhatcelik.wordpress.com/2021/02/18/step-by-step-oracle-19c-rac-installation-on-oracle-linux-7-9-part-2/

https://serhatcelik.wordpress.com/2021/02/20/step-by-step-oracle-19c-rac-installation-on-oracle-linux-7-9-part-3-database/

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/networking_guide/sec-configuring_ip_networking_with_ifcg_files

https://oracle-base.com/articles/linux/linux-network-configuration#:~:text=The%20%22%2Fetc%2Fsysconfig%2Fnetwork%2Dscripts%2Fifcfg,configuration%20for%20a%20DHCP%20adapter.