diff --git a/README.md b/README.md
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--- a/README.md
+++ b/README.md
@@ -1215,7 +1215,7 @@ Graphs can be used to represent many problems in computer science, so this secti
             - rough overview of any key algorithm that drives the service
             - consider bottlenecks and determine solutions
     - Exercises:
-        - [Design a CDN network: old article](http://repository.cmu.edu/cgi/viewcontent.cgi?article=2112&context=compsci)
+        - [Design a CDN network: old article](https://kilthub.cmu.edu/articles/Globally_distributed_content_delivery/6605972)
         - [Design a random unique ID generation system](https://blog.twitter.com/2010/announcing-snowflake)
         - [Design an online multiplayer card game](http://www.indieflashblog.com/how-to-create-an-asynchronous-multiplayer-game.html)
         - [Design a key-value database](http://www.slideshare.net/dvirsky/introduction-to-redis)