I am currently in the process of transferring a legacy website (from a legacy hosting service provider) to a modern solution. Due to my context-specific requirements (which include financial constraints), I made the decision to backup and replicate the website on a Digitalocean droplet (a virtualized linux instance) which has a static IP address 104.131.187.206. I have already configured everything appropriately, cleaned up the various loose ends that come from duplicating a Web application that is tightly coupled to its system, etc and the duplicate website is working perfectly fine.
Now, my goal is to point the existing domain name mcbc.on.ca to the new duplicate website on the DO droplet. The IP address of the legacy (shared) hosting provider is 216.251.32.98. Obviously mcbc.on.ca has been pointing to this address all this time. What I want is for mcbc.on.ca to point to 104.131.187.206. Furthermore, I am still using the legacy hosting provider for DNS and nameserver.
My task should be straightforward - simply modify the existing A entry for mcbc.on.ca in the Zone file so that it now points to 104.131.187.206. Now, I also wanted to keep an existing reference to the original website, so I added a new A entry for original.mcbc.on.ca that points to 216.251.32.98.
I successfully completed all of this yesterday and my DNS change has successfully propagated as of now (verified using this tool). FYI, it has been approximately 12 hours since I made the change.
My problem: For some strange reason, whenever I access the website at mcbc.on.ca, it sometimes resolves to the OLD address 216.251.32.98, and some other times correctly resolves to 104.131.187.206. I'd say the frequency is about 40% for the old address and 60% for the new address. This is obviously a problem.
Considering the fact that I've waited a good amount of time (although I understand that 12 hours is certainly less than 48 hours), as well as the fact that the tool I mentioned above shows that the DNS record has propagated to ALL over the world, my suspicion is that my home Internet ISP provider has a stale DNS cache.
My question: Am I right? If not, what do you think is my problem?