Explanation
VPN Connect provides a site-to-site IPSec VPN between your on-premises network and your virtual cloud network (VCN). The IPSec protocol suite encrypts IP traffic before the packets are transferred from the source to the destination and decrypts the traffic when it arrives.
On general, IPSec can be configured in the following modes:
Transport mode: IPSec encrypts and authenticates only the actual payload of the packet, and the header information stays intact.
Tunnel mode (supported by Oracle): IPSec encrypts and authenticates the entire packet. After encryption, the packet is then encapsulated to form a new IP packet that has different header information.
Oracle Cloud Infrastructure supports only the tunnel mode for IPSec VPNs.
Each Oracle IPSec VPN consists of multiple redundant IPSec tunnels. For a given tunnel, you can use either Border Gateway Protocol (BGP) dynamic routing or static routing to route that tunnel's traffic. More details about routing follow.
IPSec VPN site-to-site tunnels offer the following advantages:
Public internet lines are used to transmit data, so dedicated, expensive lease lines from one site to another aren't necessary.
The internal IP addresses of the participating networks and nodes are hidden from external users.
The entire communication between the source and destination sites is encrypted, significantly lowering the chances of information theft.

Explanation
A load balancer improves resource utilization, facilitates scaling, and helps ensure high availability. You can configure multiple load balancing policies and application-specific health checks to ensure that the load balancer directs traffic only to healthy instances. The load balancer can reduce your maintenance window by draining traffic from an unhealthy application server before you remove it from service for maintenance.
The Load Balancing service considers a server marked drain available for existing persisted sessions. New requests that are not part of an existing persisted session are not sent to that server.
Edit Drain State: Opens a dialog box in which you can change the drain state.
If you set the server's drain status to true, the load balancer stops forwarding new TCP connections and new non-sticky HTTP requests to this backend server.
This setting allows an administrator to take the server out of rotation for maintenance purposes.
e. Edit Offline State: Opens a dialog box in which you can change the offline status.
If you set the server's offline status to true, the load balance forwards no ingress traffic to this backend server.