Our web service has numerous clients who have linked their domains to it. For instance, there is a service section example.com/client184 that one of our clients links to. To achieve this, the client had to buy a domain, for example, viktor.com and specify DNS viktor.com A 1.1.1.1.

This process raises the question of how to optimize the system so that in case of changing the DNS A record of example.com, all the clients will not need to be contacted and helped to change their DNS records. Perhaps automation could be implemented to swiftly update all the linked domains with the new DNS A record without inconveniencing the clients.

The task was completed using CNAME, allowing for a flexible linking process.

To give the client more freedom in choosing what to link to, we offer our subdomain (e.g. example.com/client184) and instruct them to link their new domain (e.g. viktor.com) to it.

Once the client has linked the domains, the IP changes become irrelevant as the client sections will always remain accessible.

Have you had any experience with CNAME implementation for website linking?

To link a slave domain to the root domain of a project, the CNAME record should be used. For example, by setting DNS viktor.com CNAME example.com.

Instead of using the A record, all clients should add a CNAME record for their domain, which will automatically change to example.com records when updated. This ensures a more flexible approach in managing changes across multiple domains.

By following DNS rules, requests to viktor.com will be redirected to the corresponding record on the root domain (example.com).

One way to optimize the system and automate the process of updating DNS A records for all linked domains is by implementing a centralized domain management system. This system would act as a middle layer between the clients' domains and your web service.

Here's a possible approach:

1. Create a domain management system that allows clients to register their domains and specify the necessary DNS A record information.

2. When a client links their domain to your web service, add an entry in the domain management system associating their domain with the corresponding service section (e.g., example.com/client184).

3. Implement a regular checking mechanism within your domain management system to monitor changes in DNS A records for the linked domains.

4. When a change is detected in the DNS A record of example.com, automatically update the DNS settings of all the linked domains stored in the domain management system.

5. To propagate the changes, you can either use DNS provider APIs or send notifications to the clients with instructions on how to update their DNS records themselves.


Here are some additional considerations to further optimize the system and automate the updating of DNS A records for linked domains:

1. API Integration: Integrate your domain management system with popular DNS providers' APIs, such as Amazon Route 53 or Cloudflare. This will allow you to programmatically update DNS records without relying on manual configuration changes.

2. Time-to-Live (TTL): Set a low Time-to-Live value for the DNS records associated with the linked domains. This will help in propagating the changes quickly and reduce the time required for clients to see the updated records.

3. Batch Updates: Instead of updating DNS records for each linked domain individually, batch the updates together. This can be achieved by grouping the changes based on DNS provider or other criteria, minimizing the number of API calls and speeding up the process.

4. Notification System: Implement a notification system that proactively alerts clients about upcoming DNS changes or maintenance activities. This will help them stay informed and minimize any potential disruptions caused by the updates.

5. Rollback Mechanism: In case of any issues or errors during the DNS record update process, have a rollback mechanism in place to revert changes and restore the previous configurations. This ensures that clients do not face extended periods of downtime due to failed updates.

6. dоcumentation and Support: Provide clear dоcumentation and support channels for clients to assist them in the process of updating DNS records independently. This can include step-by-step instructions, FAQs, and responsive customer support to address any queries or issues they may encounter.