Martin Lormes recently acquired an Arduino and Ethernet shield. Once he got the setup running on the web using the Webduino Arduino web server library, he checked the traffic using Wireshark and noticed that if the embedded server didn’t offer up a favicon.ico file when initially requested the browser would keep requesting the file. This required the Arduino server to continuously generate a “400 error” message in response to each request. He decided to modify the Webduino code adding a default favicon.ico (“Hello world”) response, based on the icon used in the “Web_Image” example that ships with Webduino. This way a file is provided on the initial browser request and cached, lowering Arduino server traffic load over time.