Creating a DNS Alias for a DDNS Domain

I recently added the DNS CNAME record home.colcan.ca to my colcan.ca domain. The new record is an alias for colcan.dyndns.info. A DNS query on the former looks like this:

$ host home.colcan.ca 8.8.8.8
Using domain server:
Name: 8.8.8.8
Address: 8.8.8.8#53
Aliases: 

home.colcan.ca is an alias for colcan.dyndns.info.
colcan.dyndns.info has address 70.51.85.201

This was interesting for me because home.colcan.ca is the internal domain that I use in my home network. This domain used to work only while connected at home, it was never public. The domain colcan.dyndns.info is the one I chose for my DDNS service long ago, which I have used to reach my home router when being outside home. With this new alias I can use now home.colcan.ca consistently no matter where I am.

Why is this good? Well, there are a couple of reasons: First, I don’t have to juggle between the internal and the DDNS names when accessing my home services (storage, photo album, and so on) anymore depending on my physical location, which simplifies the configuration of my client applications. Second, it makes creating SSL certificates simpler because I can use the same SSL certificate for the home.colcan.ca domain on both the internal and the external faces of my home network.

This last point was really the trigger for me to look into this DNS alias option. I used the SSL certificates service from Let’s Encrypt to move all HTTP services to HTTPS. Having a single domain for every service, both inside and outside my home network, made configuring the SSL certificates much easier.