DNS prefetching should be emphasized in website Optimization)

Website optimization technology is always evolving. I read the previous front-end optimization notes again today.
And found 34 optimizations for yslow
Guidelines for reducing DNS
Reduce DNS
The lookups part should be corrected.

DNS
As a basic Internet protocol, the speed of resolution seems to be easily overlooked by website optimization personnel. Browser vendors are currently targeting DNS
Optimized, a typical DNS
DNS resolution takes 20-120 milliseconds to reduce
The number of resolutions is an optimized method, and DNS can be reduced.
The time for parsing is also economically beneficial. This is why browser vendors attach importance to DNS
The main reason for prefetching. DNS prefetching can be used for performance gains
Synchronous requests to asynchronous "to explain, that is, the domain name with this attribute does not need to be clicked on the link to parse in the background, and domain name resolution and content loading is a serial network operation, therefore, this method can reduce user waits.
Time to improve user experience.

Google Chrome has built-in DNS prefetching
Technology (note that there are several minor versions that have caused performance problems due to this feature), and Firefox 3.5 has introduced this new feature.
. For IE
8. You cannot see any actions for the moment (maybe I didn't notice it ?).

For a website, if you want to make full use of this function on the user's browser, you can add the link attribute anchor on the page. For example:

<LINK rel = "DNS-prefetch" href = "http://www.google-analytics.com/">

In addition, it is also necessary to use this X-DNS-prefetch-control. This may be especially useful if some websites reference some Google service scripts.

Another acceleration DNS
The approach is to consider using pdnsd
Cache DNS
Proxy Server to accelerate some DNS
Request.

In Chrome, you can enter about: histograms/DNS in the address bar.
To observe some interesting DNS
Performance data.

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