This chapter covers
- How Uniform Resource Locators identify a resource and how to access it
- The hierarchical structure of the Domain Name System
- The DNS name resolution process
- Implementing a DNS on Cisco IOS devices
“What’s in a name?” Ask that to a computer, and you’ll learn that the answer is a number. Although we humans like to use memorable names to refer to the resources we access over a network (i.e., websites), computers use numbers—IP addresses—to identify each other. So when you type a name like “www.google.com” into a web browser’s address bar, how does your computer learn the IP address of the server that hosts Google’s website?
The answer is the Domain Name System (DNS). Using DNS, your computer resolves—or translates—the name “www.google.com” into the IP address of the appropriate server. DNS is one of the foundational protocols of the internet and is necessary knowledge not just for network engineers but for professionals in nearly any area of IT. DNS is the second half of CCNA exam topic 4.3: Explain the role of DHCP and DNS within the network. In this chapter, we’ll delve into the mechanics of DNS, its significance in network operations, and how to implement it on Cisco IOS.