linux系统中高速缓存以及dns的配置解析
高速缓存
服务端：
1.配置yum源：vim /etc/yum.repos.d/rhel_dvd.repo
http://172.25.254.71/rhel7 更改yum源地址
2.yum clean all 清空缓存
3.yum repolist 列出可下载软件
4.yum install bind -y 安装bind软件
5.systemctl start named 打开服务(注意：打开服务时加密字符不够按键盘或动鼠标)
6.cat /dev/random 查看加密字符
7.netstat -atnlupe | grep named 查看named服务的53端口状态
8.rpm -qc bind 查看bind软件配置文件
9.vim /etc/named.conf 编辑配置文件
内容：
options {
listen-on port 53 { any; }; 打开服务端网络接口的所53端口
listen-on-v6 port 53 { ::1; };
directory "/var/named";
dump-file "/var/named/data/cache_dump.db";
statistics-file "/var/named/data/named_stats.txt";
memstatistics-file "/var/named/data/named_mem_stats.txt";
allow-query {any; }; 打开所有人的访问权限
forwarders { 172.25.254.250; }; 服务端不知道，访问的ip
10.systemctl restart named 重启服务
客户端：
1. vim /etc/resolv.conf 编辑配置文件
内容：
# Generated by NetworkManager
domain example.com
search example.com ilt.example.com
nameserver 172.25.254.171 访问的主机ip
2. dig www.baudu.com 询问dns域名服务器，并把缓存保存在高速缓存中
注意访问时：
REFUSED 表示访问被拒绝
NOERROR 表示访问成功
dig www.baudu.com 服务没开
; <<>> DiG 9.9.4-RedHat-9.9.4-14.el7 <<>> www.baudu.com
;; global options: +cmd
;; connection timed out; no servers could be reached
dns解析
一.dns本地正向解析
1.修改dns解析地址 vim /etc/resolv.conf
# Generated by NetworkManager
search ilt.example.com
nameserver 172.25.254.171
2.vim /etc/named.conf 编辑配置文件
内容：
options {
listen-on port 53 { any; };
listen-on-v6 port 53 { ::1; };
directory "/var/named";
dump-file "/var/named/data/cache_dump.db";
statistics-file "/var/named/data/named_stats.txt";
memstatistics-file "/var/named/data/named_mem_stats.txt";
allow-query {any; };
3.vim /etc/named.rfc1912.zones 编辑配置文件
内容：
zone "westos.com" IN { 域名
type master;
file "westos.com.zone"; 问题答案
allow-update { none; };
4. rpm -ql bind 查找配置文件
/etc/NetworkManager/dispatcher.d/13-named
/etc/logrotate.d/named
/etc/named
/etc/named.conf
/etc/named.iscdlv.key
/etc/named.rfc1912.zones
/etc/named.root.key
/var/named/named.localhost 本地解析配置文件模板
5. cd /var/named/ 进入目录ls
6. cp -p named.localhost westos.com.zone 复制配置文件
7.vim westos.com.zone 编辑配置文件
内容：
$TTL 1D
@ IN SOA @ root.westos.com. (
0 ; serial
1D ; refresh
1H ; retry
1W ; expire
3H ) ; minimum
NS dns.westos.com.
dns A 172.25.254.171
www A 172.25.254.202
hello A 172.25.254.203
8.systemctl restart named 重启服务
本机测试：dig hello.westos.com
二.dns本地反向解析：
1.修改dns解析地址：vim /etc/resolv.conf
2.vim /etc/named.rfc1912.zones 编辑配置文件
内容:
zone "254.25.172.in-addr.arpa" IN {
type master;
file "westos.com.ptr";
allow-update { none; };
3. cp -p named.loopback westos.com.ptr 复制配置文件
4. vim westos.com.ptr 编辑配置文件
内容：
$TTL 1D
@ IN SOA @ root.westos.com. (
0 ; serial
1D ; refresh
1H ; retry
1W ; expire
3H ) ; minimum
NS dns.westos.com.
dns A 172.25.254.200
110 PTR yun.westos.com.
112 PTR hello.westos.com.
5.systemctl restart named 重启服务
本机测试：dig -x 172.25.254.110
注意：本地(正向/反向)解析时，若named配置文件找不到该域名/IP地址，会访问失败。
三.dns轮询
1.在/var/named目录下
修改配置文件： vim westos.com.zone
$TTL 1D
@ IN SOA @ root.westos.com. (
0 ; serial
1D ; refresh
1H ; retry
1W ; expire
3H ) ; minimum
NS dns.westos.com.
dns A 172.25.254.108
hello CNAME www
www A 172.25.254.111
www A 172.25.254.122
2.systemctl restart named 重启服务
3.本地解析时，域名解析出现轮询式
本地测试：dig hello.westos.com
四.dns集群(辅助主机解析)
1.辅助主机配置yum源，安装bind，打开named服务
2.辅助主机修改DNS配置文件: vim /etc/resolv.conf
# Generated by NetworkManager
search example.com
nameserver 172.25.254.171
3.辅助主机修改配置文件:vim /etc/named.rfc1912.zones
zone "westos.com" IN {
type slave;
masters {172.25.254.171;};
file "slaves/westos.com.zone";
allow-update { none; };
};
4.systemctl restart named 重启服务
5.本地主机修改配置文件:vim /etc/named.rfc1912.zones
zone "westos.com" IN {
type master;
file "westos.com.zone";
allow-update { none; };
allow-transfer {172.25.254.171;}; 允许171主机同步
also-notify {172.25.254.171;}; 当文件变更时，通知171主机
};
6..本地主机修改文件:vim westos.com.zone
$TTL 1D
@ IN SOA @ root.westos.com. (
050201 ; serial 最后一次修改时间
1D ; refresh
1H ; retry
1W ; expire
3H ) ; minimum
NS dns.westos.com.
dns A 172.25.254.171
hello CNAME www
www A 172.25.254.101
www A 172.25.254.102
7.systemctl restart named 重启服务
8.测试：本地主机：dig hello.westos.com
五.dns双向解析(171主机)
1.cd /var/named/ 进入目录
2.cp -p westos.com.zone westos.com.inter 复制配置文
3.vim westos.com.inter
内容：
$TTL 1D
@ IN SOA dns.westos.com. lee.westos.com. (
2018042603 ; serial
1D ; refresh
1H ; retry
1W ; expire
3H ) ; minimum
NS dns.westos.com.
dns A 192.168.0.207
hello CNAME www
www A 192.168.0.207
dong A 192.168.0.203
4.cp -p /etc/named.rfc1912.zones /etc/named.rfc1912.inter
5.vim /etc/named.rfc1912.inter 编辑配置文件
内容：
zone "westos.com" IN {
type master;
file "westos.com.inter";
allow-update { none; };
allow-transfer { 172.25.254.107; };
also-notify { 172.25.254.107; };
};
6.vim /etc/named.conf 编辑配置文件
内容：
注释：
/*
zone "." IN {
type hint;
file "named.ca";
};
include "/etc/named.rfc1912.zones";
include "/etc/named.root.key";
*/
添加：
view localnet {
match-clients { 172.25.254.207; }; 主的访问
zone "." IN {
type hint;
file "named.ca";
};
include "/etc/named.rfc1912.zones";
};
view Anynet {
match-clients { any; }; 其他人访问
zone "." IN {
type hint;
file "named.ca";
};
include "/etc/named.rfc1912.inter";
};
7.systemctl restart named 重启服务
8.测试(107)：dig dong.westos.com
切换另一台主机(207)：vim /etc/resolv.conf 更改dns解析地址
9.systemctl restart named 重启服务
内容：
# Generated by NetworkManager
search example.com
nameserver 172.25.254.107
测试：dig dong.westos.com
六.远程更新dns解析
1. vim /etc/resolv.conf
内容：
# Generated by NetworkManager
search example.com
nameserver 172.25.254.207
2.vim /etc/named.conf
内容:
注释：
/*
view localnet {
match-clients { 172.25.254.207; };
zone "." IN {
type hint;
file "named.ca";
};
include "/etc/named.rfc1912.zones";
};
view Anynet {
match-clients { any; };
zone "." IN {
type hint;
file "named.ca";
};
include "/etc/named.rfc1912.inter";
};
*/
打开：
zone "." IN {
type hint;
file "named.ca";
};
include "/etc/named.rfc1912.zones";
include "/etc/named.root.key";
3.systemctl restart named 重启服务
4.vim /etc/named.rfc1912.zones 编辑文件
内容：
zone "westos.com" IN {
type master;
file "westos.com.zone";
allow-update { 172.25.254.107; }; 允许谁更新我的
allow-transfer { 172.25.254.107; };
also-notify { 172.25.254.107; };
};
5.systemctl restart named 重启服务
6.cp -p westos.com.zone /mnt/ 把文件备份到/mnt/
7.ls -ld /var/named/ 查看目录权限
8.chmod g+w /var/named/ 改变目录权限
9.[root@localhost named]# setenforce 0 selinux改成警告
测试(107)：
10.[root@localhost named]# nsupdate
> server 172.25.254.207
> update delete www.westos.com 删除www.westos.com
> send 发送
11.[root@localhost named]# nsupdate
> server 172.25.254.207
> update add dong.westos.com 86400 A 172.25.254.107 添加dong.westos.com(86400表示86400秒是一天)
> send 发送
查看(207)：
[root@localhost named]# ls
data named.empty slaves westos.com.zone
dynamic named.localhost westos.com.inter westos.com.zone.jnl
named.ca named.loopback westos.com.ptr
查看有westos.com.zone.jnl文件
恢复文件：
1.rm - fr westos.com.zone.jnl 删除文件
2.cp -p /mnt/westos.com.zone . 把/mnt/文件复制回来
3.systemctl restart named 重启服务
