We normally use domain name in accessing a homepage like:
http://www.yahoo.com
However, if your computer is accessing to the Internet directly without using a proxy server, it will need to first resolve this domain name (in this case www.yahoo.com) into IP address before it will try to get data from the website.
As for this example, if you look up the IP address for www.yahoo.com, you will get information such as:
C:\nslookup
Default Server: dns3.maxonline.com.sg
Address: 202.156.1.58:53> www.yahoo.com
Server: dns3.maxonline.com.sg
Address: 202.156.1.58:53Name: www.yahoo-ht3.akadns.net
Address: 209.131.36.158
Aliases: www.yahoo.com
So, using the IP address of www.yahoo.com in this case (209.131.36.158), you should be able to access the Yahoo site at: http://209.131.36.158.
Sound interesting? All come back to IP address in TCP/IP world!