Python Flask Tutorial: How to Use a Custom Domain Name for Our Application

Adding a custom domain to a Flask app deployed on a private Linux server hinges on one practical sequence: buy a domain, point its DNS to the server’s DNS provider, then create the right DNS records so traffic lands on the app—typically with a short wait while changes propagate. Once that chain is in place, users can reach the application by name (e.g., www.myawesomeapp.com) instead of an IP address, and the app’s routes, login flows, and other endpoints work normally.

The process starts with registering a domain through a domain registrar such as Namecheap (alternatives like Google Domains and GoDaddy are mentioned). Domain availability is often the hardest part: short, memorable names are frequently taken, and making offers doesn’t guarantee success. After selecting a domain (the tutorial uses myawesomeapp.com), the buyer checks out—usually for about $10–$12 per year—and considers add-ons. A key privacy feature is WHOISGuard, which hides personal registration details (name, address, phone, email) that would otherwise appear in WHOIS lookups.

With the domain purchased, the next step is switching the domain’s name servers to the DNS provider used for the application’s infrastructure. The tutorial uses Linode’s name servers (ns1.linode.com through ns5.linode.com). This change is made in the registrar’s control panel by replacing the registrar’s default DNS (e.g., “Namecheap Basic DNS”) with a custom DNS configuration pointing to Linode. Propagation isn’t instant: Linode’s documentation suggests up to 48 hours, though the tutorial reports it often resolves in roughly 15–30 minutes.

After name servers are updated, Linode’s Cloud Manager is used to create a domain zone and add DNS records. The tutorial focuses on an A record: host name “www” mapped to the Flask server’s public IP address. The IP is retrieved from Linode’s dashboard (or from the server’s networking/SSH details). This is the core mapping that tells the internet where www.myawesomeapp.com should go.

A further step sets reverse DNS on the Linode server. Reverse DNS performs the opposite lookup of standard DNS—resolving an IP address back to a domain name. In Linode’s networking settings, the tutorial edits reverse DNS to include the domain (e.g., www.myawesomeapp.com). If an error appears (“unable to perform a lookup”), it’s treated as a propagation delay; waiting resolves it.

Once DNS and reverse DNS settle, the domain is tested in a browser. The Flask application loads through www.myawesomeapp.com, and functional checks confirm that authentication, creating/updating/deleting posts, profile picture updates, and password reset emails all work under the domain. The tutorial also notes that myawesomeapp.com without “www” may not work immediately; fixing that requires adding a second A record with an empty host name pointing to the same IP.

Finally, the tutorial flags that the site is currently served over HTTP rather than HTTPS, which means the browser may mark it as “not secure.” That security upgrade is left for a later tutorial. The takeaway is that custom domains are mostly a DNS choreography problem: correct name servers, correct A records, and patience while the internet catches up.