在負(fù)載均衡的使用中，***理解的都是網(wǎng)站的域名分配了。它所使用的是DNS負(fù)載均衡技術(shù)，這項(xiàng)將技術(shù)基本上在各大網(wǎng)站上都有體現(xiàn)，那么為了讓大家更好的理解這個(gè)知識(shí)，我們搜集了一些名站的服務(wù)器資料，來(lái)幫助到家消化下這些內(nèi)容。

1、新浪

新浪采用了ChinaCache做的CDN系統(tǒng)，ChinaCache在全國(guó)分布了四十多個(gè)點(diǎn)，同時(shí)采用基于動(dòng)態(tài)分配的全球DNS負(fù)載均衡技術(shù)。

從新浪的站點(diǎn)結(jié)構(gòu)可以看出：

> www.sina.com.cn

Server: UnKnown

Address: 192.168.1.254

Non-authoritative answer:

Name: libra.sina.com.cn

Addresses: 61.135.152.71, 61.135.152.72, 61.135.152.73, 61.135.152.74 61.135.152.75, 61.135.152.76, 61.135.153.181, 61.135.153.182, 61.135.53.183, 61.135.153.184, 61.135.152.65, 61.135.152.66, 61.135.152.67, 61.135.12.68, 61.135.152.69, 61.135.152.70

Aliases: www.sina.com.cn, jupiter.sina.com.cn

在北京地區(qū)ChinaCache將www.sina.com.cn 的網(wǎng)址解析到libra.sina.com.cn，然后libra.sina.com.cn做了DNS負(fù)載均衡技術(shù)，將libra.sina.com.cn解析到61.135.152.71等16個(gè)ip上，這16個(gè)ip分布在北京的多臺(tái)前臺(tái)緩存服務(wù)器上，使用squid做前臺(tái)緩存。如果是在其它地區(qū)訪問(wèn)http://www.sina.com.cn可能解析刮..??的效果。

我們?cè)倏匆粋€(gè)新浪其它頻道是指到哪里的：

> news.sina.com.cn

Server: UnKnown

Address: 192.168.1.254

Non-authoritative answer:

Name: libra.sina.com.cn

Addresses: 61.135.152.65, 61.135.152.66, 61.135.152.67, 61.135.152.68 61.135.152.69, 61.135.152.70, 61.135.152.71, 61.135.152.72, 61.135.152.73 61.135.153.178, 61.135.153.179, 61.135.153.180, 61.135.153.181, 61.135.153.182 61.135.153.183, 61.135.153.184

Aliases: news.sina.com.cn, jupiter.sina.com.cn

可以看出，各個(gè)頻道的前臺(tái)緩存集群與www.sina.com.cn的前臺(tái)緩存集群是相同的。#p#

2、搜狐

Sohu與新浪的DNS負(fù)載均衡技術(shù)原理差不多，下面是nslookup的結(jié)果：

> www.sohu.com

Server: UnKnown

Address: 192.168.1.254

Non-authoritative answer:

Name: pagegrp1.sohu.com

Addresses: 61.135.132.172, 61.135.132.173, 61.135.132.176, 61.135.133.109 61.135.145.47, 61.135.150.65, 61.135.150.67, 61.135.150.69, 61.135.150.74 61.135.150.75, 61.135.150.113, 61.135.150.145, 61.135.131.73, 61.135.131.91 61.135.131.180, 61.135.131.182, 61.135.131.183, 61.135.132.65, 61.135.

132.80

Aliases: www.sohu.com

只不過(guò)libra.sina.com.cn換成了pagegrp1.sohu.com

我們?cè)賮?lái)看一下sohu的頻道：

> news.sohu.com

Server: UnKnown

Address: 192.168.1.254

Non-authoritative answer:

Name: pagegrp1.sohu.com

Addresses: 61.135.145.47, 61.135.150.65, 61.135.150.67, 61.135.150.69 61.135.150.74, 61.135.150.75, 61.135.150.113, 61.135.150.145, 61.135.131.73 61.135.131.91, 61.135.131.180, 61.135.131.182, 61.135.131.183, 61.135.132.65 61.135.132.80, 61.135.132.172, 61.135.132.173, 61.135.132.176, 61.135.133.109

Aliases: news.sohu.com

同新浪相同，用的是同樣的服務(wù)器群，這可能是因?yàn)樗麄冇玫亩际荂hinaCache的服務(wù)吧，不過(guò)sohu的名字起的有點(diǎn)土，pagegrp1，沒有 libra，pavo好聽，這名字聽起來(lái)有點(diǎn)像法語(yǔ)，比較浪漫。#p#

3、網(wǎng)易

網(wǎng)易似乎沒用ChinaCache的服務(wù)，下面是nslookup結(jié)果：

> www.163.com

Server: UnKnown

Address: 192.168.1.254

Non-authoritative answer:

Name: www.163.com

Addresses: 202.106.168.103, 202.106.168.104, 202.106.168.109, 202.106.168.121 202.108.36.153, 202.108.36.155, 202.108.36.156, 202.108.36.167, 202.108.36.172 202.108.36.196

直接在www.163.com 這個(gè)域名上用了DNS負(fù)載均衡技術(shù)。這樣的話就要求服務(wù)器必須放的非?？拷鞴?jié)點(diǎn)，才能保證各地的用戶訪問(wèn)的速度。

但163不同的頻道是放在不同的緩存集群上的，這與sina，sohu有些不同，等于sina，sohu是按照地區(qū)劃分服務(wù)器集群，而網(wǎng)易按照頻道劃分服務(wù)器集群。

> 163.com

Server: UnKnown

Address: 192.168.1.254

Non-authoritative answer:

Name: 163.com

Addresses: 202.108.36.205, 202.108.36.206, 202.108.36.207, 202.108.36.201 202.108.36.202, 202.108.36.203, 202.108.36.204

顯然，這和www.163.com 不是一個(gè)集群，我們?cè)賮?lái)試一個(gè)：

> sports.163.com

Server: UnKnown

Address: 192.168.1.254

Non-authoritative answer:

Name: channel.cache.163.com

Addresses: 202.108.36.136, 202.108.36.208, 202.108.36.209, 202.108.36.210 202.108.36.211, 202.108.36.212, 202.108.36.213

Aliases: sports.163.com

可以看出，和上面的集群也是不同的。#p#

4、百度

百度的前臺(tái)服務(wù)器就不是很多了：

> www.baidu.com

Server: UnKnown

Address: 192.168.1.254

Non-authoritative answer:

Name: www.baidu.com

Addresses: 202.108.250.249, 202.108.249.134

> baidu.com

Server: UnKnown

Address: 192.168.1.254

Non-authoritative answer:

Name: baidu.com

Address: 202.108.250.228

> mp3.baidu.com

Server: UnKnown

Address: 192.168.1.254

Non-authoritative answer:

Name: mp3.baidu.com

Address: 202.108.249.131

只有www.baidu.com做了兩臺(tái)服務(wù)器的集群，頻道都用了一臺(tái)服務(wù)器做前臺(tái)#p#

5、一搜

> yisou.com

Server: UnKnown

Address: 192.168.1.254

Non-authoritative answer:

Name: yisou.com

Addresses: 202.165.102.114, 202.43.217.14, 202.43.217.15, 202.43.217.16 202.43.217.17, 202.165.102.111, 202.165.102.112, 202.165.102.113

> www.yisou.com

Server: UnKnown

Address: 192.168.1.254

Non-authoritative answer:

Name: www.yisou.com

Addresses: 202.43.217.17, 202.165.102.111, 202.165.102.112, 202.165.102.113 202.165.102.114, 202.43.217.14, 202.43.217.15, 202.43.217.16

> mp3.yisou.com

Server: UnKnown

Address: 192.168.1.254

Non-authoritative answer:

Name: www.yisou.com

Addresses: 202.165.102.113, 202.165.102.114, 202.43.217.14, 202.43.217.15 202.43.217.16, 202.43.217.17, 202.165.102.111, 22.165.102.112

Aliases: mp3.yisou.com

前臺(tái)做了8臺(tái)服務(wù)器的緩存集群，www.yisou.com和 yisou.com以及mp3.yisou.com是用的同一個(gè)集群。

通過(guò)前面的分析我們可以得到一個(gè)結(jié)論：sina和sohu使用了CDN與GSBL與DNS負(fù)載均衡技術(shù)，每個(gè)地區(qū)一組前臺(tái)服務(wù)器群，網(wǎng)易，百度使用了DNS負(fù)載均衡技術(shù)，每個(gè)頻道一組前臺(tái)服務(wù)器，一搜使用了DNS負(fù)載技術(shù)，所有頻道共用一組前臺(tái)服務(wù)器集群。