DNS for the DB System

You can use DNS and hostname resolution for the DB system.

Oracle recommends using a private DNS resolver to enable the use of hostnames when on-premises hosts and VCN resources communicate with each other.

The following table shows which choices are supported with each type of DB system, and the endpoints that need to be resolved for the DB system to function.

DB System Type Supported DNS Choices Endpoints to Be Resolved
Single-node virtual machine
  • Recommended: Default (Internet and VCN resolver)
  • Custom DNS resolver of your choice
  • Object Storage endpoints (includes both the Object Storage endpoints and Swift endpoints)
  • Oracle YUM repo endpoints
Multi-node RAC virtual machine
  • Default (Internet and VCN resolver)
  • Object Storage endpoints (includes both the Object Storage endpoints and Swift endpoints)
  • Oracle YUM repo endpoints
  • Single Client Access Names (SCANs)

The following sections give more details about the DNS choices.

Default (Internet and VCN Resolver)

See the preceding table for the types of DB systems that support the Internet and VCN resolver.

Oracle recommends using the Internet and VCN resolver for DNS. It's the default, built-in DNS functionality that comes with each VCN. It enables hosts in a VCN to resolve these items:

  • Hostnames of other hosts in the same VCN.
  • Hostnames that are publicly published on the Internet.

For a DB system, the Internet and VCN resolver handles resolution of all necessary endpoints: Object Storage endpoints (includes both the Object Storage endpoints and Swift endpoints), YUM repos, and SCANs (SCANs are used only with multi-node RAC DB systems).

By default, each VCN is configured to use the Internet and VCN resolver. If you plan to use a custom DNS resolver, you must configure the VCN in a different way.

Use the Internet and VCN Resolver With Your DB System

Hostname Restrictions for Using the Internet and VCN Resolver

Custom DNS Resolver

A custom DNS resolver is a DNS server that you set up in your on-premises network and maintain yourself. It must resolve the endpoints required by the DB system.

By default, the VCN is configured to use the Internet and VCN resolver. Therefore, if you instead want to use a custom DNS resolver, you must configure the VCN and DHCP options in a different way.

Use a Custom DNS Resolver With Your DB System

Hostname Restrictions When Using a Custom DNS Resolver

DNS: Between On-Premises Network and VCN

If you are using the Internet and VCN resolver and want to enable the use of hostnames when on-premises hosts and VCN resources communicate with each other, you can set up an instance in the VCN to be a custom DNS server.

For an example of an implementation of this scenario with the Oracle Terraform provider, see Hybrid DNS Configuration.

Set Up DNS for a DB System

DNS lets you use host names instead of IP addresses to communicate with a DB system.

You can use the Internet and VCN resolver (the DNS capability built into the VCN) as described in DNS in Your Virtual Cloud Network.

Alternatively, you can use your choice of DNS server. You associate the host name and domain name to the public or private IP address of the DB system. You can find the host and domain names and IP addresses for the DB system on the Database page in the Console.

To associate the host name to the DB system's public or private IP address, contact your DNS administrator and request a custom DNS record for the DB system's IP address. For example, if your domain is example.com and you want to use clouddb1 as the host name, you would request a DNS record that associates clouddb1.example.com to your DB system's IP address.

If you provide the public IP address to your DNS administrator as described above, you should also associate a custom domain name to the DB system's public IP address:

  1. Register your domain name through a third-party domain registration vendor, such as register.com.
  2. Resolve your domain name to the DB system's public IP address, using the third-party domain registration vendor console. For more information, refer to the third-party domain registration documentation.