How to Optimize DNS and Improve Search Engine Speed for Faster Loading
This guide explains the impact of recurring DNS delays on SEO for mobile and desktop, and provides instructions on how to improve perceived speed and Page Experience scores through resource-centric DNS optimization.
In the digital world, website addresses are represented as domain names, but computers communicate using numerical IP addresses. DNS (Domain Name System) plays the critical role of translating these human-readable domain names into IP addresses. In mobile page speed optimization strategies, reducing delays during this DNS lookup phase is essential.
How to Improve Page Loading Speed with DNS Optimization
The DNS (Domain Name System) is the address system used on the internet. It translates domain names that humans can understand (e.g., example.com) into IP addresses that computers understand (e.g., 192.0.2.1). DNS optimization is one of the effective ways to optimize search engine speed.
In search engine optimization, speed is heavily impacted by the load of connecting to external reference sites. In particular, resolving third-party domain latency is an essential element of modern website performance management.
When a browser accesses a page, the information from external sites it must reference includes both the connection time and the time to load the specific element. Therefore, if a connection delay occurs, a browser rendering block phenomenon may appear, negatively affecting search engine optimization and loading speed.
Comparison of DNS Technologies: Prefetch vs. Preconnect
Check the table below to see the differences between two major technologies used to enhance web performance.
| Technology Name | Main Function | Optimization Stage | Recommended Use Case |
|---|---|---|---|
| DNS Prefetch | Pre-resolves domain names into IPs | DNS Lookup | When referencing a large number of external domains |
| Preconnect | Establishes DNS + TCP + TLS connection | Full Connection | For the most critical core resource servers |
Reducing Site Loading Time with DNS Prefetch and Preconnect
When a webpage references external resources, there are ways to prepare in advance so that the DNS lookup and server connection processes do not become bottlenecks. These are DNS Prefetch and Preconnect. They directly help improve LCP (Largest Contentful Paint), one of the Google Core Web Vitals.
Loading Speed: Prefetch
Prefetch is a method where the browser pre-loads resources that the user is expected to request in the future. It encourages the browser to download resources before the user actually requests them. DNS-prefetch encourages the browser to pre-verify the domain names and IP addresses of external sites for DNS caching.
This caching method can improve page loading speed, and it can have a significant impact on loading speed, especially for pages like blogs that have a high dependency on external pages.
When used in HTML, you can specify it in the following code format. Enter the addresses that use third-party domain resources.
link rel="dns-prefetch" href="https://tistory1.daumcdn.net/"
link rel="dns-prefetch" href="https://t1.daumcdn.net/"
link rel="dns-prefetch" href="https://blog.kakaocdn.net/"
link rel="dns-prefetch" href="https://developers.kakao.com/"
link rel="dns-prefetch" href="https://fonts.googleapis.com/"Loading Speed: Preconnect
Preconnect is a method where the browser pre-establishes a connection with the server to optimize loading time. It primarily handles the following tasks in advance:
- Saves time by pre-processing the conversion of the server's domain name into an IP address.
- Pre-performs the TCP connection setup for actual data transmission.
- Pre-processes the TLS (SSL) connection setup when using the HTTPS protocol.
Below is an example using preconnect:
link rel="preconnect" href="https://fonts.googleapis.com" crossorigin
link rel="preconnect" href="https://cdn.example.com" crossorigin
Precautions for DNS Optimization
- Avoid excessive use of Prefetch and Preconnect: If you apply these functions indiscriminately to all external domains, the browser may attempt too many connections at once, causing a network bottleneck.
- Focus on critical resources: It is most efficient to specify only frequently used external domains or resources necessary for webpage loading.
- Measure actual effects: It is recommended to check LCP improvement figures using website speed measurement tools (e.g., Google PageSpeed Insights, Lighthouse).
Q1. Does DNS optimization really help with SEO?
Yes, Google considers page loading speed a major ranking factor. Reducing Time to First Byte (TTFB) through DNS optimization can lead to positive scores during search engine visibility checks.
Q2. Which should I use first, Prefetch or Preconnect?
It is efficient for network resource management to use Preconnect for the most important fonts or API servers, and DNS Prefetch for other less critical external links.
Q3. Do all browsers support these tags?
Most modern browsers (Chrome, Edge, Safari, etc.) support them. Even if an older browser does not support them, it will simply ignore the tags without causing errors in the website's operation.
A fast website not only increases user satisfaction but also receives good evaluations from search engines. Especially for modern, complex websites that use many external resources, DNS optimization is becoming increasingly important as part of web performance optimization.
- Pre-verify external domain IPs with DNS Prefetch.
- Pre-establish server connections with Preconnect.
- Manage network load by applying these only to necessary resources.
By doing so, you can see significant effects in both Search Engine Optimization (SEO) and website loading speed. If you want to speed up your website and improve the visitor experience, apply DNS optimization today!