First, when a user in the browser’s address bar type in the web site (for example: alibaba.com), then the browser will first locate through access to the domain name to IP (DNS) in order to find where to access resources, then toshiba pa3399u-1bas li-ion battery, the browser will find the following in turn:

1 browser cache: the browser will first look in its cache there is no corresponding domain name – IP matching, if good luck, here you can directly try to access resources, and if luck is down go flat.

(2) system cache: do not hit the browser’s cache, the browser will tell the operating system: “Hey, I could not find my own pocket, may be lost, I have to go there to see you”, then, a system process ( ?) the nikon d90 battery power transfer of the system to query the DNS cache, repeat one of the lucky judge …

3 routers cache

4. ISP DNS cache: to the ISP (Internet provider) to find the DNS cache server, and under normal circumstances, the ISP side cache can be found in the corresponding cache record, and should not be so back up

5 recursive search … the most frustrating happens, there is no way in front of the DNS cache hit case, ISP’s DNS server starts from the root domain name server to start recursion, the order is from. Com top level domain name server to alibaba server replacement battery for travelmate 800, and nothing found … Well, you think your site is really going to open there is what …?

Want to emphasize is, not just the first name of the site visit to do the work of such a query, in the page reference resources as domain name resolution when there is such a series of work. The most obvious is to enable the new domain name do static resource storage services, it is basically the 1 – 5 steps had to go a few times. in order for the new domain in the DNS cache server to leave a record.

First. DNS-related optimization:

General practice: DNS resolution complexity of the improper use of multi-domain access to resources will result in unnecessary performance overhead in the WPO, a lot of optimization work is very artistic battery ibm thinkpad r60 9455, both in the DNS and HTTP optimization, you can see The magic of art:

DNS optimization, of course, as little as possible the overhead caused by DNS queries, HTTP optimization in the optimization strategy, there is a single domain name to avoid deficiencies under the number of connections for multi-channel resources to download, details of implementation will be <HTTP optimization principles and methods> in detail, here is a simple way, the static resources more Domain Name Service can bypass the browser to load a single domain name resource limit on the number of concurrent connections, DNS optimization we need as little as possible of the domain name resolution, HTTP when we need to optimize the use of appropriate multi-domain services, then how to make two good optimization li-ion panasonic cga-s007 battery practices are able to implement it? [todo]

Graceful degradation: in some modern browsers (Google Chrome, Firefox 3.5 +), it had to support the DNS pre-fetching, and how a pre-fetch it? Is loaded in the browser page, the Web page <link> or <a> the href attribute of the domain name for the background of pre-analytical (above 1 – step 5), and the analytical results will be cached in the browser when the user click on the link in real time, eliminating the need for DNS resolution in the present consumption, this consumption has shifted to the user’s browser can not perceive the process to go.

First, modern browsers have support and on by default, DNS Prefetch feature of course you can also configure the browser to manage this function:

With Firefox3.5 + can be: the default browser will open the HTTP protocol under the DNS prefetching, turned off by default HTTPS protocol under the DNS prefetching, through about: config in network.dns.disablePrefetch and network.dns. disablePrefetchFromHTTPS <two options to control the two protocols under the prefetching.

Second, you can use meta information to inform the browser compaq presario m2000 replacement battery, I need to do this DNS prefetching page

Third, you can use the link tag to force the DNS pre-fetching to do