[kasajian]

One minute into it, the article says, "The dmac and smac are pretty self-explanatory fields"

This immediately turns off anyone reading it who doesn't know what those things mean. The thought process will be, "Oh, this article is for those for whom these fields are self-explanatory. Since it's not for me, I'll stop reading"

[howerj]

The full quote would be "The dmac and smac are pretty self-explanatory fields. They contain the MAC addresses of the communicating parties (destination and source, respectively).", it does explain them. However, this is an article about how to make a network stack, it is safe to assume the reader should know something about networking before hand.

[petee]

Unless they just updated it, the next sentence explained it -

> They contain the MAC addresses of the communicating parties (destination and source, respectively).