Learning Objectives

By the end of this chapter, you will be able to:

  • Define an IP address and its purpose.
  • Differentiate between IPv4 and IPv6.
  • Define the Domain Name System (DNS) and explain its function.

Internet Addresses: IP Addresses

Every device connected to the internet is assigned a unique identifying number called an Internet Protocol (IP) address. This address works like a street address, allowing data to be routed to the correct destination.

There are two versions of IP addresses:

  • IPv4: The original version. It consists of four numbers separated by periods (e.g., 192.168.1.1). IPv4 can support about 4.3 billion unique addresses.

  • IPv6: A newer version created because the world was running out of IPv4 addresses. It uses a much longer format and can support a virtually limitless number of addresses.

The Domain Name System (DNS)

While computers use numerical IP addresses to identify each other, humans find it much easier to remember names. The Domain Name System (DNS) is the internet’s phonebook. It is a global system that translates human-readable domain names (like www.google.com) into their corresponding numerical IP addresses that computers use.

When you type a domain name into your web browser:

  1. Your computer sends a request to a DNS server.
  2. The DNS server looks up the domain name in its database and finds the corresponding IP address.
  3. It sends the IP address back to your computer.
  4. Your computer then uses that IP address to connect to the web server for the site you want to visit.

Summary

Every device on the internet has a unique numerical IP address to identify it. Because these numbers are hard for humans to remember, the Domain Name System (DNS) acts as a global directory, translating the easy-to-remember domain names that we use (like www.google.com) into the IP addresses that computers need to communicate.

Key Takeaways

  • An IP address is a unique numerical label for a device on the internet.
  • DNS translates domain names into IP addresses.
  • IPv6 was created to solve the problem of running out of IPv4 addresses.

Discussion Questions

  1. Using the phonebook analogy, explain the role of DNS.
  2. Why was it necessary to create IPv6?
  3. What do you think would happen to the internet if the DNS system suddenly stopped working?