Technical SEO

DNS Prefetch

Quick Definition

DNS prefetch is a browser hint (`<link rel="dns-prefetch" href="//example.com">`) that asks the browser to resolve a third-party domain's DNS early so subsequent requests are faster.

In context

DNS prefetch is the lightest-weight resource hint — cheaper than preconnect (which also opens TCP and TLS) and useful when you have many third-party domains where you cannot afford full preconnect overhead. Common use: prefetching analytics domains, font CDNs, image hosts, and embedded media providers. Modern best practice: use preconnect for the 2–4 most critical third parties, dns-prefetch for the long tail.

Example

A Canadian publisher with embeds from 12 third-party platforms uses dns-prefetch on all 12 plus preconnect on the top 3 — measurably reducing the cumulative connection-setup latency for embedded content.

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Preload

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