当用nginx做负载均衡的时候，nginx的配置文件如下：
upstream server_pools {
server 10.0.0.7:80 weight=1;
server 10.0.0.8:80 weight=1;
当客户端访问时出现报错如下：
[root@lb02 ~]# curl www.hahaetiantian.org
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>400 Bad Request</title>
</head><body>
<h1>Bad Request</h1>
<p>Your browser sent a request that this server could not understand.<br />
</p>
<p>Additionally, a 400 Bad Request
error was encountered while trying to use an ErrorDocument to handle the request.</p>
</body></html>
[root@lb02 ~]# curl www.hahaetiantian.org
www查看日志报错并不能找到原因，但是根据400报错以及对http协议的原理了解得知是因为请求头的原因，最后在网上找到解决办法，原因是因为upstream后面的名称有下划线使得代理无法识别，修改如下：
upstream server-pools {
server 10.0.0.7:80 weight=1;
server 10.0.0.8:80 weight=1;然后再次访问结果如下：
[root@lb02 ~]# curl www.etiantian.org
apache www
[root@lb02 ~]# curl www.etiantian.org
www