What is DNS lookup?

Today, the Domain Name System (DNS)—often called the internet’s phonebook—along with DNS lookup helps users navigate the internet without having to remember long, complex IP addresses of individual sites.

Since its invention more than 40 years ago, DNS lookup has become one of the most reliable processes on the internet, enabling many core functionalities like browsing, email and mobile applications.

When a user enters the domain name of a site into their web browser, DNS translates the site into its IP address and the user is immediately taken there. This process is known as forward DNS lookup. The reverse is also possible through a process called reverse DNS lookup that converts IP addresses into their domain name, or hostname.

Today, DNS lookup use cases are expanding alongside newer technologies like the Internet of Things (IoT) and edge computing, which are causing the number of devices connected to the internet to rise dramatically. According to a recent report, the number of IoT devices like smart thermostats and wearable fitness trackers reached 17 billion this year, and the number of mobile phones surpassed 8 billion connections.¹

DNS lookup is typically broken down into three steps:

1. User request and local cache resolution
2. Hierarchical name server lookup
3. Response delivery

Here’s a closer look at each step and how it enables the technology to function.

DNS lookup begins with a user making a simple request for a webpage. This request is done by entering a domain name into a web browser, a process known as a DNS query.

When the user types the address of the site they want to visit into the web browser, the query is forwarded to the user’s internet service provider (ISP) by a DNS forwarder—a server on the local network that the user is accessing. The DNS forwarder gathers DNS queries from other users and servers on the network and forwards them to off-site domains that are outside the network.

DNS query resolution begins with a DNS resolver, or recursive DNS server, a type of DNS server designed to translate readable domain names into IP addresses through communication with other DNS servers. First, the DNS resolver checks its local cache, which is its stored memory on a local network.

If the correct IP address for the site the user has entered is stored—or cached— there, the process stops. However, if the corresponding IP address isn’t located in the local cache, the DNS resolver must proceed to the next step.

If the IP address for the domain a user has entered isn’t cached locally, the DNS resolver contacts a series of name servers in hierarchical order. This type of server stores IP addresses and their corresponding domain names.

First, it contacts root name servers, a directory that stores a list of top-level domain names (TLDs) on the World Wide Web that end in .com, .org and .net, as well as the ones that end in country-codes like .uk or .ca.

If the searched domain isn’t listed in the root name server directory, the DNS resolver next checks a directory of TLD name server. Here it can find information about the authoritative name server, a type of server that stores definitive DNS records—sets of instructions used to connect domain names with internet protocol (IP) addresses. Examples of definitive DNS records include canonical names (CNAMES) and mail exchange server (MX server) records.

DNS response delivery involves the DNS resolver delivering the correct IP address for the domain a user has requested back to the user’s device. The response can come either from the local cache or from an authoritative name server following a recursive search.

It can all appear deceptively simple to the user. The process is typically accomplished in milliseconds, giving the user a fast, seamless browsing experience.

Once considered a simple tool that translated domain names into IP addresses, DNS lookup has become an essential part of modern IT infrastructure. Here’s a closer look at its benefits.

While DNS lookup might have once seemed like a background function of the internet, it has since evolved to keep up with new technologies like cloud computing, IoT and artificial intelligence (AI). This evolution kept it is as relevant today as it was when it first appeared.

For example, consider the IT department of a multinational organization that operates across numerous countries and territories. DNS lookup enables it to easily and securely add subdomains to its site as its business grows.

Each subdomain can be managed within the DNS with its own unique record, even if it is just a translation of a site from another language. This method allows a single domain (for example, IBM.com) to be divided into separate, smaller sections that can be individually managed in the territories where their content is relevant.

Security issues and the rise of cybercrime are other areas where DNS lookup has had to evolve, driving many recent DNS innovations. It includes the transition to IPv6 and the development of DMARC, a policy that makes sending and receiving emails safer. According to a recent report, 1 in every 174 DNS queries is malicious, a significant increase from the previous year when only 1 in every 1,000 queries was a threat.²

Despite its rich history and promising future with new technologies, DNS lookup isn’t without its challenges. Here are some of the areas where it struggles:

• DNS propagation: When DNS records need to be updated, it can take time to propagate the necessary changes globally. Record changes often negatively affect time to live (TTL)—a measurement of the time it takes for a DNS server to open cached records.

• New security risks: DNS lookup has effectively grown and developed alongside the modern internet, developing new capabilities as use has spread, but security vulnerabilities remain. Cache poisoning, spoofing and amplification attacks are just a few examples of vulnerabilities that will require further investment and innovation in the future for the technology to remain safe and reliable.

• IPv6 adoption: While IPv6 (Internet Protocol version 6, the most recent internet protocol that was designed to accommodate the rapidly growing number of devices that use the internet) has been largely successful. It has added a layer of complexity to DNS lookup that causes challenges. For example, IPv6 and its predecessor IPv4 require two different types of DNS records: A records for IPv4 and AAAA records for IPv6, making adoption of IPv6 challenging for some new users.

• Validation: DNS records like SPF and DMARC need to be properly configured to ensure trust and compliance. IPv6 validation issues often stem from incorrect records and unreachable IPv6 addresses, as well as compatibility challenges with legacy systems.

• Troubleshooting: As more devices connect to the internet, the number of DNS record types is going to keep growing. Because of this growth, troubleshooting complexity will most likely continue to be an issue for IPv6 and subsequent IP versions in the future.

DNS lookup tools have become fundamental to the infrastructure of most modern enterprises, enabling employees and users to safely access the internet and underpinning many core applications. Here are five of its most compelling use cases at the enterprise level.

Even with the rise of workplace productivity apps like Asana and Slack, email remains a core communication and collaboration technology for most organizations. DNS lookup enables the use of mail exchange records (MX records), a type of DNS record that ensures email traffic reaches the correct email servers and that email sources are validated.

Today’s most successful cloud services, such as AWS, Google Docs and Salesforce, depend on APIs and DNS to be effective. DNS records like CNAME records and SRV records enable enterprises to map APIs to resources, ensuring they can be secured and easily scaled to support different cloud environments.

Load balancing, distributing network traffic among multiple servers to ensure app availability, relies on DNS lookup and the configuration of DNS records across multiple DNS servers. If a critical piece of infrastructure like a data center or network fails, load balancing allows traffic to be rerouted to avoid disruption.

As the internet has grown, complying with different data laws across multiple territories has become a challenge for global enterprises. DNS queries and authoritative DNS logs give organizations a comprehensive compliance trail for audits so they can swiftly identify areas for improvement and avoid costly penalties for violations.  

DNS resolution is fundamental to the rise of the Internet of Things (IoT) and edge computing, networks of physical devices that process data closer to the source rather than in a data center. DNS resolution connects central servers that are critical to IoT and edge environments, reducing latency and creating stronger user experiences for smart appliances and other edge devices.