What should you do to make a website accessible via a specific URL on App Engine?

To make a website accessible via a specific URL on App Engine, verifying domain ownership with Webmaster Central and creating a DNS CNAME record is a crucial process. This step ensures that you have control over the domain you want to use for your application. Verifying domain ownership is an important first step in configuring a custom domain, as it provides Google with assurance that you have authority over the domain.

After ownership is verified, creating a DNS CNAME record is necessary for directing traffic from your custom domain to your App Engine application's serving endpoint. The CNAME record corresponds to the custom domain you want to use and points it to App Engine's provided URL, effectively integrating your application with the custom domain.

This approach aligns with best practices for custom domain setup in cloud environments, as it facilitates the easy management and routing of network traffic to your App Engine services. The other options involve strategies that are not applicable or do not follow the required initial verification steps, which are essential for using a custom domain effectively.