Chapter 13. Cloud DNS: managed DNS hosting
This chapter covers
- An overview and history of the Domain Name System (DNS)
- How the Cloud DNS API works
- How Cloud DNS pricing is calculated
- An example of assigning DNS names to VMs at startup
DNS is a hierarchical distributed storage system that tracks the mapping of internet names (like www.google.com) to numerical addresses. In essence, DNS is the internet’s phone book, which as you can imagine is pretty large and rapidly changing. The system stores a set of “resource records,” which are the mappings from names to numbers, and splits these records across a hierarchy of “zones.” These zones provide a way to delegate responsibility for owning and updating subsets of records. For example, if you own the “zone” for yourdomain.com, you can easily control the records that might live inside that zone (such as, www.yourdomain.com or mail.yourdomain.com).
Resource records come in many flavors, sometimes pointing to specific numeric addresses (such as A or AAAA records), sometimes storing arbitrary data (such as TXT records), and other times storing aliases for other information (such as CNAME records). For example, an A record might say that www.google.com maps to 207.237.69.117, whereas a CNAME record might say that storage.googleapis.com maps to storage.l.googleapis.com. These records are like the entries in the phone book, directing people to the right place without them needing to memorize a long number.