This project is so simple. The Author just wants to control Lamp from out side. So, he uses Arduino and Ethernet shield to control the lamp over the internet. And here is the steps, how to have done with it.
How to Set NETWORK
Connect the Ethernet Shield to the Arduino
User must have a unique MAC Address for Ethernet shield. ( Ex. 90:0F:97:A2:0F:ED)
Preparing Ethernet Shield as a Web Server
Before starting programming, it is necessary to assign an IP Address for Ethernet Shield. This IP will be the Web Server IP and remotely providing the data provided by Arduino.
The figure below shows a possibility of connection between the router and the Ethernet Shield.
Send Ping Packet to Ethernet Shield
To verify that the Ethernet Shield has a valid IP, User can send Ping message and must return Ping reply message from Ethernet Shield.
If there is reply messages, Now Ethernet shield can send or receive data over internet.
Arduino + Ethernet Shield + Relay + Lamp – Hardwired
This is the home page provided by Web Server.