Section 2 - Domain Naming
At the end of Section 1, we examined a simple Internet operation -
a hypertext page transfer. Remember these key points?
A Web browser requested this URL: http://www.FreeSoft.org/Connected/index.html
The DNS protocol was used to convert www.FreeSoft.org into the
32-bit IP address 205.177.42.129
The HTTP protocol was used to construct a
GET /Connected/index.html message
A table lookup in /etc/services revealed that HTTP uses
TCP port 80
The TCP protocol was used to open a connection to 205.177.42.129, port 80,
and transmit the GET /Connected/index.html message
The IP protocol was used to transmit the TCP packets to 205.177.42.129
Some media-dependent protocols were used to actually transmit the
IP packets across the physical network
Over the next few sections in this course, we'll be looking at each step
of this procedure at a high level of detail.
In this section, we'll examine the DNS protocol, used in the second step
to convert the hostname
www.FreeSoft.org into 205.177.42.129,
the 32-bit numeric address
used by the TCP and IP protocols.