Note

You use the Domain Name Server DHCP option to specify the DNS Type for the associated subnet. If you change the option's value, either restart the DHCP client on the instance or reboot the instance. Otherwise, the change does not get picked up until the DHCP client refreshes the lease (within 24 hours).

DEFAULT CHOICE: INTERNET AND VCN RESOLVER
This is an Oracle-provided option that includes two parts:

Internet Resolver: Lets instances resolve hostnames that are publicly published on the internet. The instances do not need to have internet access by way of either an internet gateway

or a connection to your on-premises network (such as a Site-to-Site VPN IPSec connection through a DRG

).
VCN Resolver: Lets instances resolve hostnames (which you can assign) of other instances in the same VCN. For more information, see About the DNS Domains and Hostnames.

By default, new VCNs you create use the Internet and VCN Resolver. If you're using the Networking API, this choice refers to the VcnLocalPlusInternet enum in the DhcpDnsOption object.
Note

By default. the Internet and VCN Resolver does not let instances resolve the hostnames of hosts in your on-premises network connected to your VCN by Site-to-Site VPN or FastConnect. That functionality can be achieved either by using a custom resolver or by configuring the VCN's private DNS resolver.
CUSTOM RESOLVER
Use DNS servers of your choice for resolution (maximum three). They could be DNS servers that are:

Available through the internet. For example, 216.146.35.35 for Dyn's Internet Guide.
In your VCN.
In your on-premises network, which is connected to your VCN by way of a Site-to-Site VPN or FastConnect (through a DRG

).


Reference: https://docs.oracle.com/en-us/iaas/Content/Network/Concepts/dns.htm...