Explanation/Reference:
Explanation:
Network groups provide a method for VMs to be grouped together for communications and firewall rules.
You can define network groups to allow VMs within a group to communicate with each other, while also preventing those VMs from communicating outside the group.
Note:
Access rule. Access rules define the permitted paths of communication for VMs that are within a network group. You can define an access rule to enable a specific path of communication between two network groups, or between a network group and a specified list of IP addresses.
References: http://www.oracle.com/webfolder/technetwork/tutorials/obe/cloud/dbaas/OU/IntroDBaaS/ ConfiguringNetworkSettings/ConfiguringNetworkSettings.html#section2s2