To prevent cheating in exams many countries restrict or even shut down Internet access during critical exam hours. I wrote two weeks ago about Syria having planned Internet shutdowns during June, for exams.
Sudan is doing the same thing and has had four shutdowns so far. Here's the Internet traffic pattern for Sudan over the last seven days. I've circled the shutdowns on Saturday, Sunday, Monday and Tuesday (today, June 22, 2021).
Cloudflare Radar allows anyone to track Internet traffic patterns around the world, and it has country-specific pages. The chart for the last seven days (shown above) came from the dedicated page for Sudan.
The Internet outages start at 0600 UTC (0800 local time) and end three hours later at 0900 UTC (1100 local time). This corresponds to the timings announced by the Sudanese Ministry of Education.
Further shutdowns are likely in Sudan on June 24, 26, 27, 29 and 30 (thanks to Twitter user _adonese for his assistance). Looking deeper into the data, the largest drop in use is for mobile Internet access in Sudan (the message above talks about mobile Internet use being restricted) while some non-mobile access appears to continue.
That can be seen by looking at the traffic mix from Sudan. During the exam times mobile use drops (as a percentage of traffic) and desktop use increases. This chart also shows how popular mobile Internet access is in Sudan: it's typically above 75% of traffic (compare with, for example, the US).
If you want to follow the other outages for the remaining five exams, you can see live data on the Cloudflare Radar Sudan page.