CDN & Global
Anycast Test: Discover Your Nearest CDN PoP
Anycast routing sends your traffic to whichever CDN edge BGP says is closest, but BGP closeness is not always geographic closeness. The Anycast Test identifies which point of presence (PoP) you actually land on for major CDNs and compares it to where you would expect to land based on your location.
What It Measures
This tool measures anycast routing behavior by querying CDN diagnostic endpoints that report which PoP served your request. It identifies your routed PoP for Cloudflare, Google, AWS CloudFront, and Fastly, then shows the distance and latency to each.
How It Works
- Issues diagnostic requests to anycast endpoints on major CDNs
- Parses the served PoP identifier from each response
- Maps each PoP to its geographic location
- Shows you which CDN provides the best routing from your network
Why It Matters
If your traffic to Cloudflare lands in Los Angeles instead of Seattle when you live in Portland, every Cloudflare hosted site (which is millions of sites) is slower than it should be. Anycast misrouting is invisible to traditional diagnostics but directly affects your daily browsing latency. Knowing your routed PoPs helps you push your ISP for better peering.
Understanding Your Results
Routed PoP latency should be under 30ms for most users in major metros, under 50ms in secondary cities, and under 100ms in remote areas. Your routed PoP should generally be in the same region you live in. Routing to a PoP in a different country or coast indicates a peering issue worth raising with your ISP.
Frequently Asked Questions
What is anycast routing?
Anycast is a routing technique where the same IP address is announced from multiple locations worldwide. BGP routes each user to whichever announcement is shortest in BGP terms (lowest AS path length, then other metrics). It allows CDNs to serve all users from a single IP while transparently directing each to a nearby edge.
Why does anycast not always pick the closest PoP?
BGP closeness uses AS path length and policy, not geographic distance or latency. Two ISPs may exchange traffic at a peering point that forces some users to a more distant PoP. Some routes are chosen for cost reasons by transit providers. The result is that anycast usually picks well, but not always optimally.
How can I get better routing?
Most users cannot directly influence BGP. The most common path to better routing is providing this data to your ISP and asking them to peer more directly with the CDNs you depend on. Some VPNs offer better PoP routing. Switching ISPs to one with better peering in your area is another option.
Which CDNs use anycast?
Cloudflare, Google Cloud (including Google Cloud CDN), AWS CloudFront, Fastly, Akamai, Microsoft Azure Front Door, and most modern CDNs use anycast for both performance and DDoS resistance. Each maintains a different PoP footprint, so the optimal CDN for your location may differ from the most popular one globally.
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