Different CF Domains Route Differently to Same Origin

I have two different domains in Cloudflare, both of which have records routing to the same origin server. When logged in to a Linode VPS in Dallas (I believe Linode is a Cloudflare peering partner) and attempt to reach domain #1, the network path goes to Miami with 30-32 ms latency. When I trace to domain #2 with the exact same destination origin server IP located in Utah, it routes one hop out of Linode’s network and responds in 1.5 ms, a 15-fold difference. I’m assuming this is a Dallas-based Cloudflare instance.

Any ideas why this might be the case? Why does one domain go the opposite direction from the origin server and away from the local Cloudflare entry point, while the other takes the more reasonable path when both are going to the same origin server?

There are a variety of factors that can affect the route that your request takes. These include (but are not limited to):

  • The plan that the domain is on. Enterprise get priority routing, for example. Not sure about Pro/Business but I would assume they also get priority over Free.
  • Which IP address Cloudflare is broadcasting for your domain (because Cloudflare is an anycast network the IP that is used may be different for different domains).
  • The peering of the networks you take to reach Cloudflare (not just your origin network, also ones on the path to the domain).

Unfortunately there’s little you can do as the user to resolve this, it’s entirely dependant on a lot of factors out of your control. For what it’s worth, 1.5ms compared to 30ms is unlikely to make a difference to your users.

Ironically, the domain with the bad path is a Pro plan, while the other is Free. It just seems really weird that the path here would go to Miami of all places. Sure, it might not hit the closest data center, but I’d expect something at least nearby (and/or closer to the origin), like Houston, Omaha, Denver, Salt Lake City, Chicago, and so on.

It’s definitely not causing any problems with the sites. I just happened to notice this when troubleshooting some unrelated server issues over the weekend.

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