What is Paas, Hosting and SaaS [closed]

Question

Wikipedia to the rescue.

PaaS - Platform as a service

http://en.wikipedia.org/wiki/Platform_as_a_service

SaaS - Software as a service

http://en.wikipedia.org/wiki/Software_as_a_service

Hosting

http://en.wikipedia.org/wiki/Internet_hosting_service

Heroku is not a DNS registrar. You can however buy domains elsewhere, such as Godaddy and add them to your Heroku app. By default you are given a free my-app-name.herokuapp.com domain. After you have purchased a domain, to "point it at heroku", you'll need to add a CNAME record which points to your my-app-name.herokuapp.com domain.

When you purchase a domain, you'll need to host the records on a DNS server. Some registrars provide free DNS hosting, others charge extra for it. You can purchase DNS hosting from Amazon Route 53 for $0.50 per domain / month. To use Amazon, you would need to change the domain's name servers to Amazon's.

Domain > Name Server > Hosting provider / PaaS.

One limitation of using Heroku is that you cant use apex domains. You must use a subdomain eg. www.example.com instead of just example.com. This is a DNS limitation - you can't have CNAME records on the apex. It must be an A record. Amazon Route 53 is one of the few providers that allow virtual CNAME records on the apex. It's basically an A record that is frequently updated. Each time your Heroku app sleeps due to inactivity, you may be given a new ip address when it restarts.