How It Works: The browser pre-resolves the DNS for example.com during page load. When a resource from example.com is requested, the DNS lookup is already done, speeding up the request. Points to Note: Do not include http: or https:, just // to make it protocol-relative. If the domain uses https, modern browsers may not prefetch unless the site is also served over https. Use it only for domains you are sure you will need, as unnecessary prefetching can waste bandwidth.