[root@localhost ~]# curl http://mirror.centos.org/centos/
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>AZENCO</title>
<style type="text/css">
body{ background:#F5F5F5; font-size:12px; font-family:Arial, Helvetica, sans-serif; color:#333;}
#mean { width:600px; height:300px; background:#FFF; position:absolute; margin-left:50%; left:-300px; margin-top:-150px; top:50%;
-moz-box-shadow: 2px 2px 12px #ccc;
-webkit-box-shadow: 2px 2px 12px #ccc;
box-shadow: 2px 2px 12px #ccc;
 }
 #mean .text { margin:10px ; font-size:14px; text-align:center;}
#mean  .logo { width:200px; height:80px; background:url(/etc/squid/errors/logo.jpg) no-repeat; margin:40px auto ;}
#mean .text h2 { font-size:26px;}
</style>
</head>

<body>
<div id="mean">
<div class="logo"></div>
<div class="text">
<h2>Gд╟Rд╟е· qadaд÷an edilmiе÷dir</h2>
<p>Sayta giriе÷ informasiya texnologiyalarд╠ idarи≥si tи≥rи≥findи≥n baд÷lanд╠b</p>
</div>
</div>

</body>
</html>

<BR clear="all">
<HR noshade size="1px">
<ADDRESS>
Generated Thu, 17 Nov 2011 12:15:18 GMT by localhost.localdomain (squid/2.6.STABLE6)
</ADDRESS>
</BODY></HTML>

[root@localhost ~]# cat /etc/yum.repos.d/CentOS-Base.repo | grep -v ^#

[base]
name=CentOS-$releasever - Base
baseurl=http://mirror.centos.org/centos/$releasever/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

[updates]
name=CentOS-$releasever - Updates
baseurl=http://mirror.centos.org/centos/$releasever/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

[extras]
name=CentOS-$releasever - Extras
baseurl=http://mirror.centos.org/centos/$releasever/extras/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

[centosplus]
name=CentOS-$releasever - Plus
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

[contrib]
name=CentOS-$releasever - Contrib
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=contrib
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

[root@localhost ~]# cat /etc/yum.repos.d/CentOS-Base.repo | grep -v ^#

[base]
name=CentOS-$releasever - Base
baseurl=http://mirror.centos.org/centos/$releasever/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

[updates]
name=CentOS-$releasever - Updates
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

[extras]
name=CentOS-$releasever - Extras
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

[centosplus]
name=CentOS-$releasever - Plus
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

[contrib]
name=CentOS-$releasever - Contrib
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=contrib
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

[root@localhost yum.repos.d]# yum update
Loaded plugins: fastestmirror, presto
Loading mirror speeds from cached hostfile
Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=6&arch=i386&repo=os error was
14: HTTP Error 403 : http://mirrorlist.centos.org/?release=6&arch=i386&repo=os
Error: Cannot find a valid baseurl for repo: extras