In a previous post I talked about the different layers of the TCP/IP. At the application layer I mentioned user friendly addresses, such as URLs as www.bentley.edu . the question that arises is how does the computer know where that URL references to. The Domain name System protocol (DNS) is responsible for translating this URL/domain name into an IP address. The question is how does it do so, especially when there are an infinite number of addresses? When you enter any URL in your web browser and hit the enter key the following happens to return the IP address used to request the page. Keep in mind that this protocol usually uses UDP because the data requested is relatively small.

1)      A query is generated from your internet explorer sends it to a local domain name server.

2)      The query runs within the local DNS table and checks if the IP address is within this database. If it is available it is sent back to the DNS client application, which sends it back to the HTTP client (internet browser)

3)      If the local DNS table doesn’t contain  that URL the local DNS server sends the root server. The root server returns an IP address of the closest top-level servers.

4)      The query runs through the top level server and looks up the top level part of the URL; the .com or .edu.

5)      Then another query is run form the top level domain, querying to an authoritative DNS server, returning the IP of the local address. the Bentley in the Bentley.edu

6)      The IP address is then returned to the DBNS client and then returned to the HTTP client (web browser)