The Domain Name System (DNS) Architecture

- The DNS - The Phonebook of the Internet

The Domain Name System (DNS) is the phonebook of the Internet. Humans access information online through domain names, like example.com. The DNS is a distributed database in which you can map hostnames to IP addresses through the DNS protocol from a DNS server. Each unique IP address can have an associated hostname.

Web browsers interact through Internet Protocol (IP) addresses, and other service information. DNS translates domain names to IP addresses so browsers can load Internet resources. Each device connected to the Internet has a unique IP address which other machines use to find the device. DNS servers eliminate the need for humans to memorize IP addresses such as 192.168.1.1 (in IPv4), or more complex newer alphanumeric IP addresses such as 2400:cb00:2048:1::c629:d7a2 (in IPv6). But like the rest of your infrastructure, DNS today is vastly more dynamic and is a more important tool than ever for developers and operators to understand and leverage effectively. 

An important and ubiquitous function of the DNS is its central role in distributed Internet services. When a user accesses a distributed Internet service using a URL, the domain name of the URL is translated to the IP address of a server that is proximal to the user. The key functionality of DNS is that different users can simultaneously receive different translations for the same domain name. This feature of DNS to be able to provide the users with the proximal server is key to providing faster and more reliable responses on the Internet.

- Domain Names

A domain name is a human-readable name - like example.com - that we type in a web browser URL field. The Internet Corporation for Assigned Names and Numbers (ICANN) manages these domain names. 

Top Level Domain (TLD) refers to the last part of a domain name. For example, the .com in example.com is the Top Level Domain. The most common TLDs include .com, .net, org, and .info. Country code TLDs represent specific geographic locations. For example: .us represents the United States. 

Second Level Domain is the part of a domain name which comes right before the TLD - example.com - for example.

A subdomain can be created to identify unique content areas of a web site. For example, the cluster of cluster.example.com.

- Speed Up DNS Lookups

DNS lookup is a critical component of an application's performance. As the entry point into an application, the need for reliable and fast DNS lookups is obvious. Importantly, as a user is about to interact with an application, DNS also presents a powerful opportunity to manage the performance of the application by sending users to appropriate service endpoints in today’s distributed environments.

Almost all network connections require an initial DNS lookup, including both machine-to-person (M2P) and machine-to-machine (M2M) communications. Therefore, if a DNS lookup is slow to return a result, for end-users the network will “feel” slow, while for devices it could impact time-critical M2M connections.

Until recently, while application architectures and other underlying infrastructure had undergone tectonic shifts, DNS itself hadn’t kept pace and had been limited to restrictive endpoint selection techniques. In the face of modern distributed architectures, an increasingly dynamic Internet, and ever more demanding users, the need for more advanced DNS tools has rapidly emerged.