DNS (Domain Name System) functions as the internet’s phonebook, translating user-friendly domain names into IP addresses that computers understand. IP addresses are numerical representations that computers use to identify each other on a network.
By converting a domain name like “example.com” into an IP address such as “192.168.1.1,” DNS makes it easier for users to navigate the internet and access websites.
The process of mapping domain names to IP addresses is called a DNS lookup, which involves interactions between a user’s device, a recursive DNS resolver, and authoritative DNS servers.
Other terms related to DNS include DNS queries, DNS caching, reverse proxy, pointing DNS directly, and DNS records.
DNS lookup
When a user enters a domain name in their browser, a DNS query is sent to a recursive resolver. If the resolver has the IP address cached, it returns the address to the browser. If not, the resolver queries a series of DNS servers (root, top-level domain, and authoritative servers) to find the appropriate IP address.
Once obtained, the IP address is returned to the user’s browser, enabling connection to the desired website’s server. This process is called a DNS lookup.
Authoritative DNS servers and recursive DNS resolvers
An authoritative DNS server stores and provides DNS records, including IP addresses, mail servers, and subdomains, for a specific domain. It serves as the ultimate source of information for that domain.
In contrast, a recursive DNS resolver acts as an intermediary between the user’s device and the authoritative DNS servers. When a user requests a domain name, the recursive resolver queries the necessary DNS servers to obtain the corresponding IP address. It simplifies the DNS lookup process for the user’s device by handling server interactions and returning the IP address needed for establishing a connection to the desired website.
Types of DNS queries
There are three main types of DNS queries: recursive, iterative, and non-recursive. Each type of query plays a role in the overall process of mapping domain names to IP addresses in different situations.
- Recursive queries involve a DNS resolver performing the entire resolution process, contacting relevant servers, and providing the user’s device with the IP address.
- Iterative queries see a user’s device directly communicate with multiple servers as the resolver offers references without finding the IP address.
- Non-recursive queries are used between DNS servers, exchanging information without conducting additional queries, often for record updates or maintenance.
DNS caching
DNS caching is a process that temporarily stores DNS query results, such as IP addresses associated with domain names, to reduce latency and improve performance for subsequent requests.
When a user’s device or a recursive DNS resolver performs a successful DNS lookup, the resulting IP address is stored in the cache for a specified duration, known as the time-to-live (TTL).
If another query for the same domain name is made within the TTL, the cached IP address is returned, eliminating the need for a full DNS lookup. This optimization significantly speeds up the process and reduces the load on DNS server
Reverse proxy vs. pointing DNS directly
A reverse proxy acts as an intermediary “hall monitor” for web traffic. It’s a server that sits in front of the web servers that host your site. Instead of pointing your DNS directly to your web host, you would point it to your proxy service, which would then direct your website’s visitors to your web host.
Choosing between pointing DNS directly or using a reverse proxy depends on factors such as hosting setup, site migration speed, security, performance, and scalability.
Using reverse proxy
Consider using a reverse proxy if your main site and blog are hosted separately and the blog is a subdirectory of your main site, your host does not offer adequate security or performance, your site and mobile app share the same URL and need traffic direction, or if you want a CDN and your current host doesn’t provide one.
Pointing DNS directly
Point DNS directly if you’re hosting all content on a single host with root domains or subdomains, require a quick site migration without resources for proxy configuration, or have a secure and scalable host like WordPress VIP with a built-in CDN.
DNS records
DNS records are used for various purposes in managing and directing internet traffic. Here are five important ones:
- A Record (Address Record): Maps a domain or subdomain to an IPv4 address, allowing users to access a website using its domain name.
- AAAA Record (Quad-A Record): Similar to the A Record, it maps a domain or subdomain to an IPv6 address, ensuring compatibility with both IPv4 and IPv6 networks.
- CNAME Record (Canonical Name Record): Creates an alias for a domain or subdomain, redirecting traffic to another domain without changing the requested URL, which is useful for pointing multiple domains to the same content.
- MX Record (Mail Exchange Record): Specifies the mail servers responsible for receiving email on behalf of a domain, ensuring proper email routing and prioritization.
- NS Record (Name Server Record): Indicates the authoritative DNS servers responsible for managing a domain’s DNS records, which is crucial for maintaining accurate and consistent DNS resolution.
In summary
DNS translates user-friendly domain names into IP addresses, enabling internet navigation. During a DNS lookup, a user’s device queries a recursive DNS resolver, which interacts with authoritative DNS servers to obtain the IP address. DNS caching speeds up the process, while reverse proxies and pointing DNS directly offer different web hosting benefits.