Where's the Server?

How to play

1. 1Read the first clue: the fastest possible round trip from Johannesburg to today's server, if fibre ran in a straight line. One millisecond is roughly 100 km.
2. 2Type a city name, or tap a dot on the map, and press Guess. Only the cities in the pool are dots — Johannesburg is the origin and never the answer.
3. 3A wrong guess shows the fibre floor, the distance and the compass direction from the city you guessed to the server, and draws a ring around your guess on the map.
4. 4Where two rings cross is where the server is. Each wrong guess also unlocks a clue: hemisphere, then continent, then the name's first letter, then the country.
5. 5Find the city within five guesses. Share your emoji trail, then measure your real ping and see how far above the physical floor it sits.

Latency is distance

Light in a vacuum covers 300 000 km every second. Inside the glass core of an optical fibre it slows to roughly two-thirds of that — about 200 000 km/s, or 200 km every millisecond. A ping is a round trip, so every 100 km between you and a server costs a millisecond before a single router has done anything. That number is the fibre floor, and it is the only clue you start with.

It is also why the numbers on a speed test look the way they do. A Johannesburg fibre line pinging a Johannesburg server can show 2 to 5 ms; the same line pinging London cannot physically show less than about 91 ms, however good the ISP.

Straight-line great-circle distance and the round-trip floor at 200 km/ms. Real routes are longer.

Why your real ping is higher than the floor

No cable runs in a straight line. The subsea systems that connect South Africa — WACS and Equiano up the west coast, SEACOM and EASSy up the east — follow the continent's coastline before turning towards Europe or Asia, which adds thousands of kilometres. Every router, switch and amplifier on the path adds a little queuing delay, your ISP's own network adds a few milliseconds, and Wi-Fi at home can add ten or more on its own.

A measured ping of 150 to 180 ms from Johannesburg to London is therefore normal and not a fault. What you can influence is the part between your device and your ISP: a wired connection, a router that is not overloaded, and a provider that peers well locally. The methodology page explains how we separate those parts.

Why every puzzle starts in Johannesburg

Because most of South Africa's internet does. NAPAfrica, the largest internet exchange point on the continent, and the Teraco data-centre campus around it are where South African ISPs, content networks and cloud providers hand traffic to one another. When your speed test picks a nearby server, this is usually where it is — which is why a good Gauteng fibre line pings in single digits and a Cape Town one pings the same servers at 12 ms or more.

Those campuses run through load-shedding on their own power; whether your line does depends on your router's battery and your provider's tower or exchange. If yours drops, the guide on keeping your internet on through load-shedding covers the cheap fixes.

Frequently asked questions

What is the fibre floor?

The fastest round trip physics allows between Johannesburg and the city, if the fibre ran in a straight line. Light in glass travels at about 200 000 km per second, so a round trip costs one millisecond per 100 km. Real pings are always higher because cables follow coastlines and every router adds a little delay.

Why is Johannesburg always the starting point?

Most South African internet traffic is exchanged there, at NAPAfrica and the surrounding data-centre campuses, which is also where speed-test servers usually sit. It makes the floor a number you can compare with your own ping.

How are the distances and directions calculated?

Great-circle distance on a 6 371 km sphere from published city-centre coordinates, and the initial bearing from your guess towards the server. The city table is machine-checked against reference distances, so a mistyped coordinate cannot ship.

When does a new server appear?

At midnight South African Standard Time. Everyone gets the same city on the same day, no city repeats within the pool's rotation, and your guesses are saved in your browser so you can come back to an unfinished puzzle.

Is any of this sent to a server?

No. Guesses, streaks and results stay in your own browser's localStorage. The only network request the page can make is the optional speed test on the home page, which you start yourself.