What Is DNS? A Clear Guide To The Domain Name System

DNS stands for Domain Name System, which is a system that translates domain names into IP addresses. Domain names are the human-readable addresses that we use to identify websites, while IP addresses are the numerical addresses that computers use to communicate with each other over the internet. Without DNS, we’d be left trying to memorize long strings of numbers to access our favorite websites.

When you enter a domain name into your web browser, your computer’s operating system DNS client first checks a local cache for the corresponding IP address. If the address isn’t found locally, the request is sent to a DNS server on the local area network (LAN), often a recursive resolver provided by your Internet Service Provider (ISP). The DNS server then attempts to resolve the query. If it has the record cached from a previous request, it returns the IP address immediately (this is a non-authoritative answer). If not, it will query other DNS servers, starting with the root servers, then the Top-Level Domain (TLD) servers, and finally the authoritative name servers for the specific domain, to find the correct IP address. Once found, the DNS server returns the IP address to your computer, allowing it to connect to the website. DNS servers cache these records for a period determined by the Time-to-Live (TTL) value to speed up subsequent requests.

DNS is an essential part of how the internet works, allowing us to use easy-to-remember domain names instead of having to memorize IP addresses. It also allows websites to change their IP addresses without requiring users to update their bookmarks or remember a new IP address.

Key Takeaways

DNS translates human-readable domain names into numerical IP addresses, acting as the internet’s phonebook.
Domain names follow a hierarchical structure (e.g., subdomain.domain.TLD) read right-to-left, with specific naming rules defined by RFC 1035.
DNS queries can be recursive (resolver does full lookup), iterative (resolver refers to next server), or nonrecursive (direct cached answer), with caching improving performance.
DNS traffic logs provide valuable data for forensic research, helping identify malicious activity and user browsing patterns.
Specialized DNS types like Dynamic DNS (for changing IPs) and Private DNS (for internal networks) address specific technical requirements.

DNS – Domain Name System

DNS stands for Domain Name System. It is the internet’s phone book. It helps computers talk to each other by translating domain names into IP addresses, letters, and numbers that computers use to identify themselves on the internet.

The DNS is a server hierarchy that translates human-readable website names like “amazon.com” into computer-readable numerical addresses like “198.245.240.6”. This process is called name resolution, and it works because each server has records of all the other servers that store this information in their databases.

The DNS hierarchy can be visualized as a tree with several levels of branches that branch out from root servers at the top to leaf nodes that have no additional information beyond what is stored at their parent servers and are used only by clients that ask for more specific answers than can be found in the leaf nodes’ parent servers’ databases.

DNS Structure

A URL typically contains the domain name. A domain name is composed of numerous labels. Each section of the domain hierarchy represents a subdivision and should be read from right to left.

Following the period in the domain name is the TLD (Top-Level Domain). There are several top-level domains, but some examples include .com, .org, and. edu. Certain domains, like.us for the United States or.ca for Canada, may indicate a country code or specific geographic area. Furthermore, there are industry-specific domain extensions such as .gov for government organizations, .mil for military entities, and emerging options like the .ai domain extension, which is increasingly popular for businesses and individuals associated with artificial intelligence.

There are two subdomains associated with each label on the left side of the TLD. In the URL www.techtarget.com, “techtarget” is a subdomain of.com, and “www.” is a subdomain of techtarget.com.

There can be up to 63 characters per label, and 127 levels of subdomains. Up to 253 characters can be used in the domain’s total character count. A numeric TLD name is prohibited, and labels cannot begin or end with hyphens. Request for Comments (RFC) 1035, published by the Internet Engineering Task Force (IETF), contains standards for establishing domain names.

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How Does DNS Work?

The operating system’s DNS client will search a local cache when a user inserts a human-readable address into the browser to see if there is any information. Without the desired address, it will search for a DNS server on the local area network (LAN).

As soon as the local DNS server receives the query and finds the desired domain name, it will respond. The local server will forward the request to a DNS cache server, which the Internet Service Provider frequently provides if the name cannot be retrieved (ISP).

The DNS server will swiftly respond to requests since it temporarily stores DNS records in its cache. Because they provide request resolution based on a cached value obtained from authoritative DNS servers, these DNS cache servers are known as nonauthoritative DNS servers.

A list of authoritative name servers for every top-level domain is kept up to date and made available by an Authoritative Root Name Server (.com, .org, etc.). Authoritative Top Level Domain Name Servers maintain authoritative name servers for every domain (gmail.com, wikipedia.org, etc.). It must query name servers to determine the correct authoritative name server for the specified domain.

Types of DNS Queries

DNS queries are a type of request sent to a DNS resolver. A client can query the DNS server, which response with an answer.

Recursive DNS queries

In a recursive query, the DNS client requires the DNS server to respond with either the requested resource record or an error message if the record cannot be found. The server cannot just refer the client to a different DNS server. If the server doesn’t have the answer, it will query other servers (root, TLD, authoritative) on behalf of the client until it finds the answer or confirms it doesn’t exist. This is the typical query type between a client (e.g., your computer) and its local DNS resolver.

Iterative DNS queries

In an iterative query, the DNS client allows the DNS server to return the best answer it currently has. If the queried DNS server does not have a match for the query name, it returns a referral—a pointer to an authoritative name server for a lower level of the domain namespace. The client then makes a query directly to the referred server. This process continues with additional DNS servers down the query chain until either an error or timeout occurs, or an answer is found. This is the typical query type used between DNS servers.

Nonrecursive Queries

A nonrecursive query occurs when a DNS resolver queries a DNS server that already knows the answer (because it’s authoritative for the record or the record is in its cache). The server doesn’t need to query other servers and immediately returns the result or indicates that the record doesn’t exist.

Role of DNS in Increasing Web Performance

The A records, or IP addresses, that servers obtain from DNS queries can be cached for a predetermined period. By increasing efficiency, caching enables servers to react rapidly when a request for the same IP address is received.

For instance, the local DNS server would only need to resolve the name once if everyone in the workplace needed to watch the same training video on a certain website on the same day. After that, it could serve any subsequent requests from its cache. The time the record is held — commonly known as the time to live (TTL) — is decided by administrators and relies on many criteria. Shorter time intervals offer the most accurate responses, while longer ones lessen the server load.

What is DNS Provider?

A DNS provider is the organization that hosts your Domain and utilizes Domain Name System (DNS) records to connect your Domain to email, webpages, and other web services. You can manage DNS records by accessing the DNS zone provided by your domain host. These records are vital to the operation of your website and email.

How To Check “What Is My DNS?

If you do not know where your Domain is hosted, you can find out by following the procedures:

Open this link in your web browser and input your domain name in the Domain area.
Click the DNS Lookup button below, and your domain host will be shown.

What is Private DNS?

A private DNS server is a name server that acts as an authoritative source of information for the domain names it manages. The term “private” refers to the fact that these servers are tightly controlled by their owners rather than being offered to the public.

Private DNS servers are often used when a company wants to run its DNS infrastructure but does not want its internal customers to have access to it.

Private DNS Use Cases

The following are some possible use cases for private DNS:

Custom DNS Zones Within a VCN

A private zone is a subdomain of the public zone used for internal purposes. For example, if you have a company called “mycompany.com” and a separate domain called “mycompany.myprivate.com,” you can only assign the private zone to your internal network. This is useful for companies with multiple domains or subdomains for internal use only.

Shared Private DNS Zones Within a Region

This can be useful when only a few people need Internet access but want to keep their Internet connection private from others. In this case, they can have a shared private zone that points to another authoritative name server in a different region or even another country (although this will increase latency and throughput).

Split Horizon

The split horizon technique (also known as split-view DNS) allows a DNS server to provide different answers to the same query depending on the source IP address of the querier. This means internal users querying for a domain name might get an internal IP address, while external users querying for the same domain name get a public IP address. This prevents looping by sending packets out of only one interface at a time and is useful for controlling access and routing within complex networks.

What is Dynamic DNS?

Dynamic DNS (DDNS) is a software service that allows you to automatically update the DNS record for a domain name whenever its associated IP address changes. This is particularly useful for devices or networks that have dynamically assigned IP addresses (like home internet connections) but need to be reachable via a consistent domain name.

The advantages of using dynamic DNS include the following:

Network administrators no longer need to manually reconfigure DNS settings every time an IP address changes, freeing them up to focus on overall network health.
You can access your home server, website, or other networked devices remotely using a fixed domain name, even if your home IP address changes frequently. A client application on your network periodically communicates your current IP address to the DDNS service provider, which updates the DNS record accordingly.
It eliminates the need to manually update DNS records when IP addresses change. DDNS is often more cost-effective than paying for a static IP address, especially for home or small business use.

What is DNS Traffic?

DNS traffic refers to all the query and response packets sent between clients (like your computer or smartphone) and DNS servers. Every time you browse a website, send an email, or use an internet-connected application, your device generates DNS traffic to translate domain names into IP addresses.

Why is DNS Traffic Important?

DNS plays a crucial role in how your enterprise’s end users connect to the internet. Each connection made by client devices to a domain is recorded in the DNS logs. Examining DNS traffic between client devices and your local recursive resolver may yield a plethora of information for forensic research and security monitoring.

DNS inquiries can reveal the following:

Communication patterns that might indicate botnets and malware contacting command and control (C&C) servers.
Websites visited by employees, which can be useful for policy enforcement or incident investigation.
Access attempts to known harmful domains, phishing sites, or domains generated by Domain Generation Algorithms (DGAs), which are often used by malware.
Usage of dynamic DNS (DynDNS) services, which can sometimes be associated with malicious activities.
Detection of potential DDoS attacks, such as analyzing spikes in NXDomain (non-existent domain) responses.

In addition, DNS is also essential for web deployment, allowing websites and web services to be accessible through domain names. DNS settings play a crucial role in ensuring proper web deployment and management.

What is DNS settings?

DNS settings refer to the configuration records within the Domain Name System associated with a specific domain name. These settings dictate how internet traffic directed at your domain name (e.g., for your website or email) is routed to the correct servers.

The DNS settings, also known as DNS records (like A, CNAME, MX, TXT records), control the online resolution of websites and related services (email, FTP). They are managed through a DNS Management interface, typically provided by your domain registrar or DNS hosting provider, allowing you to make various adjustments.

Typically, changing DNS settings requires time to propagate across the global network of DNS servers. This propagation time can vary from minutes to hours (or sometimes longer) depending on TTL values and caching by intermediate servers. Repeated changes might increase this propagation time; therefore, you should only alter your domain’s DNS settings if you understand the implications and are confident in the changes being made.

Final Words

So, there you have it: a brief explanation of DNS that covers all of the basics. Hopefully, some of the principles here will help you understand DNS better and figure out why it’s so important. DNS operates in a hierarchical system of servers, each responsible for a specific domain or zone. By understanding how DNS works, we can better appreciate the complex network underlying our online activities.

The Internet is only possible with this essential service. So keep your eyes peeled and pay attention to what goes underneath the hood. You never know—you might use DNS someday!

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Ahona Rudra

Domain & Email Security Expert at PowerDMARC

Ahona is the Marketing Manager at PowerDMARC, with 5+ years of experience in writing about cybersecurity topics, specializing in domain and email security. Ahona holds a post-graduation degree in Journalism and Communications, solidifying her career in the security sector since 2019.

What is DNS?