TIL: A Records vs CNAME Flattening on Cloudflare

I’ve touched DNS records for years as a sysadmin without ever really sitting down and understanding why you can’t just CNAME your root domain. Setting up Cloudflare for this site finally forced the issue.

Quick definitions if you’re newer to this: an A record (Address Record) points a domain name straight to an IP address — it’s the most direct kind of “this name means that server” mapping. A CNAME (Canonical Name Record) points a domain name at another domain name instead of an IP, so it’s really just an alias — “this name is really that other name, go look there.”

Here’s the situation. GitHub Pages hands you a set of IPs to point your domain to - Simply, these are public IP addresses pointing to servers owned by GitHub. For www.frankolwenda.com, that’s easy — CNAME it to frankolwenda.github.io and move on. But try that on the bare root domain (frankolwenda.com, no www) and DNS pushes back. A CNAME means “this name is just an alias for that other name,” full stop, and the spec won’t let an alias share space with anything else at that name — like an MX (Mail Exhanger) record for email.

So the root and the www get handled differently:

• Root domain gets A records, pointed straight at GitHub Pages’ IPs. A-records just map a domain name to an IP address, no aliasing, so they play fine with whatever else lives at that name. Put simply Root Domain --> Server IP
• www gets the CNAME, pointed at frankolwenda.github.io. Put simply Alias Domain --> Root Domain

Cloudflare also has a feature called CNAME flattening, which fakes an alias at the root by resolving it to an IP under the hood. That’s the move if your host only gives you a hostname and no static IPs. GitHub Pages gives static IPs, so I skipped it — plain A records did the job.

Small distinction, but it’s one of those things that’s completely obvious in hindsight and mildly baffling every time before you actually hit it.