Subdomains, Linode, another hosting provider for the parent domain, and a third party DNS provider ...and all that

Trying to point a subdomain at Linode, where the hosting provider is Bluehost and the DNS registrar is name.com

Common DNS Configurations (on Linode) by Elle Krout

https://www.linode.com/docs/networking/dns/common-dns-configurations

(see setting up a subdomain)DNS Manager Overview (on Linode)

https://www.linode.com/docs/networking/dns/dns-manager-overview/

Interesting Links on Domain Registrar, Name.com

Adding a NS Record:

https://www.name.com/support/articles/115005091047-Adding-an-NS-Record?keyword=subdomain

Adding a domain to Bluehost:

https://bhusers.com/add-addon-domain-bluehost/

Hosting SubDomains on Bluehost:

https://my.bluehost.com/cgi/help/361

https://en.wikipedia.org/wiki/Zone_file

(set up subdomain on bluehost, and contact name.com to modify their zone file)

Then use NAT forwarding to point a docker container at the Public IP address for the hosting Linode Server

Understand Docker Communication - Docker Docs

https://docs.docker.com/engine/userguide/networking/default_network/container-communication/

How To Forward Ports through a Linux Gateway with Iptables by Justin Ellingwood

https://www.digitalocean.com/community/tutorials/how-to-forward-ports-through-a-linux-gateway-with-iptables

(useful tutorial for inspiration)

Linux 2.4 NAT HOWTO by Rusty Russel

http://www.netfilter.org/documentation/HOWTO/NAT-HOWTO.html

http://www.netfilter.org/documentation/HOWTO/packet-filtering-HOWTO.html

But using Bluehost and Linode for hosting and Name.com for parent DNS provision and Bluehost for subdomain provision adds a layer of complexity, What about https://freedns.afraid.org/ and Linode?