Which CDN Datacenter (colo)
See which Cloudflare data centre is serving you.
Where this comes from
Cloudflare serves each request from the data centre best placed to reach you, identified by a three-letter airport code. This page reads and shows that code for your connection.
What the results mean
- Airport code
- LHR is London Heathrow, SFO San Francisco, and so on — the nearest major airport to the data centre.
- What this does not tell you
- The code identifies the edge location serving this connection, not where your traffic goes afterwards. A request that misses the cache still travels on to the origin server, wherever that is.
Common problems and fixes
- The data centre is in another country
- Usually your ISP's routing rather than a fault. Traffic is handed off wherever your provider peers, which for some mobile and business connections is a hub in a neighbouring country. A VPN does this by definition, since your traffic arrives from wherever the exit server sits.
- The code changes between page loads
- Expected behaviour. Routing responds to load and capacity, so consecutive requests can land in different locations, particularly at the edge of two regions. It only warrants attention if it correlates with a jump in latency, which the ping test will show more clearly than this one.
- I want to know why a site is slow, not which colo serves it
- This is one input rather than the answer. A distant edge location adds a few milliseconds; a saturated uplink adds hundreds. Run the latency and bufferbloat tests first — they measure the things that actually make a connection feel slow, and this figure only matters once those are clean.
Frequently asked questions
Why is my nearest data centre not the closest city?
Cloudflare routes by network topology, not straight-line distance. The nearest PoP by internet routing is usually geographically close, but peering arrangements and capacity can send you to one slightly further away. It is normal and does not indicate a problem.
What is a colo?
Short for colocation — the facility housing the servers that terminate your connection. Cloudflare labels each with the three-letter IATA code of the nearest major airport, which is why the answer reads like a flight booking. LHR is London, CDG is Paris, EWR is Newark.
Does a closer data centre mean a faster site?
It helps and it is not decisive. Physical distance sets a floor on latency, so a nearby edge is better than a distant one, but a cache miss that has to reach a slow origin server undoes the advantage entirely. Edge proximity matters most for static assets and least for anything generated per request.
Put this on your own site
Free to embed, no attribution required beyond the source link the frame carries itself. It runs entirely in your visitor's browser, sets no cookies and loads no third-party script.
<iframe src="https://runthetests.com/embed/cloudflare-colo-check/" width="100%" height="560" style="border:1px solid #e5e5e5;border-radius:8px" title="Which CDN Datacenter (colo)" loading="lazy"></iframe>
Preview it at https://runthetests.com/embed/cloudflare-colo-check/. Embedded pages are marked noindex, so yours stays the canonical copy — not this one.