简单CDN之智能DNS

智能DNS就是根据请求来源的ip来返回不同的结果，在CDN中客户的就近访问起了重要的作用。
1.编译安装bind9.6 (由于要用到bind的view功能，所以要用版本9)
tar zxvf bind-9.6.0.tar.gz
./configure --prefix=/usr/local/named --enable-threads
make&&make install

编译选项--enable-threads据说能发挥多核cpu的优势

2.2、创建named.conf文件
[root@ns bind-9.6.0]# cd /usr/local/named/
[root@ns named] #sbin/rndc-confgen >./etc/rndc.conf
[root@ns named]# cd etc/
[root@ns etc]# tail -10 rndc.conf |head -9|sed s/#\//g >named.conf
[root@ns etc]# cat named.conf




接着在下面添加配置
配置分段的，语法类似C
logging {
channel default_syslog { syslog local2; severity notice; };
channel audit_log { file "/var/log/named.log"; severity info;
print-time yes;print-category yes;print-category yes; };
category default { default_syslog; };
category general { default_syslog; };
category security { audit_log; default_syslog; };
category config { default_syslog; };
category resolver { audit_log; };
category xfer-in { audit_log; };
category xfer-out { audit_log; };
category notify { audit_log; };
category client { audit_log; };
category network { audit_log; };
category update { audit_log; };
category queries { audit_log; };
category lame-servers { audit_log; };
};

options {
directory "/var/named/";
pid-file "/var/named/named.pid";
statistics-file "/var/named/named.stats";
dump-file "/var/log/named.dump";
zone-statistics yes;
auth-nxdomain yes;
notify yes;
transfer-format many-answers;
max-transfer-time-in 60;
interface-interval 0;
listen-on-v6 { any; };
};
以上为全局配置，定义一些文件存放位置等。
接着添加用于测试
acl "TEST1"{
192.168.1.0/24;
192.168.1.213/32;
};

acl "TEST2"{
192.168.10.0/24;
192.168.1.214/32;
};

acl "OTHER_ALL"{

any;

};

view "view_test1"{

match-clients{TEST1;};
zone "fox.com"{
type master;
file "master/1/fox.com";
};
};

view "view_test2"{

match-clients{TEST2;};
zone "fox.com"{
type master;
file "master/2/fox.com";
};
};

view "view_other"{

match-clients{OTHER_ALL;};

zone "fox.com"{

type master;

file "master/other/fox.com";

};

};

acl{}用于 指定不同客户的ip地址（段）。如果ip量大可以写在外部文件中.
view{}用于对指定acl给出相对应的.def（区域数据文件）。
acl "OTHER_ALL" 匹配剩余的，view{}的顺序很关键。

bind的主配置文件就这样

3创建目录与主区域文件
mkdir /var/named
mkdir -p /var/named/master/1
mkdir -p /var/named/master/2

mkdir -p /var/named/master/3

master/1/fox.com
master/2/fox.com
包含不同请求ip地址对应的区域文件

vim master/1/fox.com

$TTL 3600
$ORIGIN fox.com.
@ IN SOA ns.fox.com. root.ns.fox.com.(
2005121013 ;Serial
3600 ; Refresh ( seconds )
900 ; Retry ( seconds )
68400 ; Expire ( seconds )
15 );Minimum TTL for Zone ( seconds )

@ IN NS ns.fox.com.
@ IN A 192.168.1.201
ns IN A 192.168.1.201
www IN A 192.168.1.11

--------------------------------------------------------------
vim master/2/fox.com

$TTL 3600
$ORIGIN fox.com.
@ IN SOA ns.fox.com. root.ns.fox.com.(
2005121013 ;Serial
3600 ; Refresh ( seconds )
900 ; Retry ( seconds )
68400 ; Expire ( seconds )
15 );Minimum TTL for Zone ( seconds )

@ IN NS ns.fox.com.
@ IN A 192.168.1.212
ns IN A 192.168.1.212
www IN A 192.168.1.22

--------------------------------------------------------

vim master/other/fox.com

$TTL 3600
$ORIGIN fox.com.
@ IN SOA ns.fox.com. root.ns.fox.com.(
2005121013 ;Serial
3600 ; Refresh ( seconds )
900 ; Retry ( seconds )
68400 ; Expire ( seconds )
15 );Minimum TTL for Zone ( seconds )

@ IN NS ns.fox.com.
@ IN A 192.168.3.212
ns IN A 192.168.3.212
www IN A 192.168.3.22

3.启动named
/usr/lcoal/bind/sbin/named -g &
如果配置文件没错，服务就在后台运行了，注意如果配置了view，那在view外边就不能设置zone 区域了。
根据配置，我们预料192.168.1.0/24 段的客户得到的地址将与192.168.10.0/24的不同，我们看下结果









结果是不一样的，实现了智能dns。
测试的dns服务器有2块网卡，分别对应192.168.1.0/24 和 192.168.10.0/24