Secure Your Network: Private DNS in Oracle Cloud Infrastructure

 Private DNS in Oracle Cloud Infrastructure (OCI) refers to a service that enables you to create and manage custom domain names within your virtual cloud network (VCN). With Private DNS, you can define custom domain names and map them to specific resources, such as Compute instances, Load Balancers, or other services within your VCN.

Key features and benefits of Private DNS in OCI include:
Custom Domain Names: You can create your own domain names, such as example.com or subdomain.example.com, tailored to your organization's needs.
Resource Mapping: Private DNS allows you to map these custom domain names to specific resources within your VCN, making it easier to manage and access your services.
Network Isolation: By using Private DNS within your VCN, you can ensure that your domain names remain private and are only accessible within your network, enhancing security and control.
Integration with Oracle Services: Private DNS seamlessly integrates with other Oracle Cloud services, enabling you to easily manage domain names for resources such as Compute instances, Load Balancers, and more.
Automation and Scalability: You can automate the creation and management of domain names using OCI's APIs, CLI, or Terraform, making it easy to scale and manage your infrastructure.
Overall, Private DNS in OCI provides a flexible and secure way to manage domain names and map them to resources within your virtual cloud network, facilitating efficient communication and management of your cloud infrastructure.
Now, the objective of this post is to give an idea on how we can communicate to the resources using their hostnames. As we know, DNS is a feature which translates hostnames to IP addresses. If we have resources in OCI and they don't know the respective hostnames, then the communication can't be established. To mitigate this problem, OCI has the option of Private DNS in OCI.
A small use case here.
When we provision a compute instance, it comes with its own fully qualified domain name example oraclevcn.com. Now, if i need to set it to samappsdba.com, we need to perform some additional steps.
The high level steps
Private DNS Zone – which contain DNS data from the VCN (like IP address)
Private DNS Views – this is collection of Zones, Zone can only belong to a single View.
Private DNS Resolver – you can assign Views to Resolver which will then resolve those DNS queries for you. Remember the order, first custom views, then default and finally from Internet

Once the A record is added and published, we can do the test

[opc@instance-20240328-1959 ~]$ host -t NS samapspdba.com

samapspdba.com name server vcn-dns.oraclevcn.com.

[opc@instance-20240328-1959 ~]$

 

After I delete it the private view

 

@instance-20240328-1959 ~]$ host -t NS samapspdba.com

samapspdba.com name server vcn-dns.oraclevcn.com.

[opc@instance-20240328-1959 ~]$ nslookup www.samapspdba.com

Server:         169.254.169.254

Address:        169.254.169.254#53

 

** server can't find www.samapspdba.com: REFUSED

This is a basic demonstration on how using private DNS feature in OCI, we can customize the hostname. 

I hope this post helps someone.