Your business may need its own CDN, i.e. when you want to get permanent cache or need guaranteed bandwidth and resources.
To create your own CDN, you will need a domain name or a subdomain, at least two servers (dedicated or virtual) in different locations, and a geoDNS tool to redirect user requests to the nearest server.
It is noteworthy that you can build a DNS server with geoDNS functionality from scratch, but it will be more efficient to use ready-made solutions.