DNS is a very popular and well known protocol. It is used for resolving host names and domain names to IP addresses. The fact is that when you type www.firewall.cx the name is translated into an IP address via a number of queries that take place from your PC towards the DNS server. This DNS Query process (and more) is analysed in great depth in the articles that follow.

The amount of information covering the DNS protocol has been broken into smaller sections to help avoid confusion and make the learning process as easy as possible.

Following is a break-down of the articles provided and information they contain:

Section 1: The DNS Protocol. How and why the DNS protocol was born. Page contains a bit of historical information and also compares DNS with the OSI Reference model, where you will see the layers on which DNS works. Internet DNS hierarchy is also analysed here, giving you the chance to understand how domains on the Internet are structured.

Section 2: The DNS Resolution Process. What really happens when a host requests a DNS resolution. Full analysis of the whole resolution process using a real life example. Understand Name Servers and the role they play in the DNS system.

Section 3: The DNS Query Message Format. This section, along with the next one gives you the DNS packet format in all its glory. Learn how DNS queries are generated and formatted. See, learn and understand the various fields within the packets as your taken through a full detailed analysis of the packet structure using the cool 3D diagrams.

Section 4: The DNS Response Message Format. This is the continuation of the section above, dealing with the DNS response that's received. You will learn how the response packet is generated, formatted and sent to the resolver. Again, you're taken through a full detailed analysis of the packet structure using the cool 3D diagrams.