1. UNIT 2 LESSON 9 CS PRINCIPLES

2. UNIT 2 LESSON 9 OBJECTIVES Students will be able to: Explain the inefficiencies of everyone managing their own name-to- address table. Describe the protocols necessary for users to update and utilize DNS to translate a human-readable location on the Internet into a numeric IP address.

3. DNS The DNS is a hierarchical system that maps information such as IP addresses to domain names. It enables Internet users to connect human-language locations on the Internet with numeric addresses used by IP. While distributed and hierarchical, it can be treated in the abstract as a centralized registry of locations on the Internet, allowing users to quickly find locations they are looking for and register themselves so that others may find them.

4. DNS When computers talk to one another on the web, they don’t refer to each other by names; they use an IP address to indicate who they are and who they are sending a message to. Without this system, the packets would be impossible to route across the Internet. The problem with this system is that, while computers are fine with referring to other computers by numbers, humans are really terrible at remembering long strings of seemingly-random numbers. We’d prefer to identify a web page by its name, and besides, it makes remembering our favorite locations on the Internet (“Code.org” vs. 174.129.14.120) much easier!