DNS的負載均衡和遞歸與疊代查詢

一、DNS的負載均衡

//DNS伺服器資源解析記錄的類型：  
//     NS:DNS伺服器聲明記錄
//     A：正向解析記錄
//     CNAME：解析記錄的别名
//     PTR：反向解析記錄

// 我們可以配置多個伺服器來實作負載均衡

[root@tk ~]# cat /var/named/test.cn.zone
$TTL 1D
@       IN SOA  @ rname.invalid. (
                                        0       ; serial
                                        1D      ; refresh
                                        1H      ; retry
                                        1W      ; expire
                                        3H )    ; minimum
test.cn. NS     tk
tk      A       10.0.0.200
www     A       10.0.0.201
www     A       10.0.0.202
[root@tk ~]#  systemctl  restart named

           

二、 DNS的泛域名解析

//  DNS的泛域名解析，就是都比對不到的時候，此時就會比對到*的位址
[root@tk ~]# cat /var/named/test.cn.zone
$TTL 1D
@       IN SOA  @ rname.invalid. (
                                        0       ; serial
                                        1D      ; refresh
                                        1H      ; retry
                                        1W      ; expire
                                        3H )    ; minimum
test.cn. NS     tk
tk      A       10.0.0.200
www     A       10.0.0.201
www     A       10.0.0.202
*       A       1.1.1.1
[root@tk ~]#

// 我們進行測試
[root@gitlab ~]# nslookup abc.test.cn
Server:         10.0.0.200
Address:        10.0.0.200#53

Name:   abc.test.cn
Address: 1.1.1.1

[root@gitlab ~]# nslookup www.test.cn
Server:         10.0.0.200
Address:        10.0.0.200#53

Name:   www.test.cn
Address: 10.0.0.201
Name:   www.test.cn
Address: 10.0.0.202

[root@gitlab ~]#
           

三、 DNS的解析記錄的别名

// 解析别名可以讓我們此時的解析結果與其他的域名一樣
[root@tk ~]# cat /var/named/test.cn.zone
$TTL 1D
@       IN SOA  @ rname.invalid. (
                                        0       ; serial
                                        1D      ; refresh
                                        1H      ; retry
                                        1W      ; expire
                                        3H )    ; minimum
test.cn. NS     tk
tk      A       10.0.0.200
www     A       10.0.0.201
www     A       10.0.0.202
abc     A       10.0.0.203
*       A       1.1.1.1
bieming CNAME   abc
[root@tk ~]#

[root@gitlab ~]# nslookup abc.test.cn
Server:         10.0.0.200
Address:        10.0.0.200#53

Name:   abc.test.cn
Address: 10.0.0.203

[root@gitlab ~]# nslookup bieming.test.cn
Server:         10.0.0.200
Address:        10.0.0.200#53

bieming.test.cn canonical name = abc.test.cn.
Name:   abc.test.cn
Address: 10.0.0.203

[root@gitlab ~]#

           

四、遞歸查詢

// 虛拟機B：建構DNS伺服器負責b.test.cn
[root@gitlab ~]# yum -y install  bind  bind-chroot
[root@gitlab named]# cat /etc/named.conf
//
// named.conf
options {
        directory       "/var/named";
};
zone "b.test.cn" IN {
        type master;
        file "b.test.cn.zone";
};

[root@gitlab named]# cat b.test.cn.zone
$TTL 1D
@       IN SOA  @ rname.invalid. (
                                        0       ; serial
                                        1D      ; refresh
                                        1H      ; retry
                                        1W      ; expire
                                        3H )    ; minimum
b.test.cn.      NS      gitlab
gitlab  A       10.0.0.205
www     A       10.10.10.10
[root@gitlab named]#

[root@gitlab named]# systemctl restart named
 
虛拟機A:子域授權

[root@tk ~]# cat /var/named/test.cn.zone
$TTL 1D
@       IN SOA  @ rname.invalid. (
                                        0       ; serial
                                        1D      ; refresh
                                        1H      ; retry
                                        1W      ; expire
                                        3H )    ; minimum
test.cn. NS     tk
b.test.cn. NS   gitlab
tk      A       10.0.0.200
gitlab  A       10.0.0.205
www     A       10.0.0.201
www     A       10.0.0.202
abc     A       10.0.0.203
*       A       1.1.1.1
bieming CNAME   abc
[root@tk ~]#
[root@tk ~]# systemctl restart named

// 虛拟機B：測試
[root@gitlab named]# nslookup  www.b.test.cn
Server:         10.0.0.200
Address:        10.0.0.200#53

Non-authoritative answer:
Name:   www.b.test.cn
Address: 10.10.10.10


           

五、疊代查詢

[root@tk ~]# cat /etc/named.conf
//
// named.conf
//
options {
        directory "/var/named";
        // 禁用遞歸查詢
        recursion no;
};

logging {
        channel default_debug {
                file "data/named.run";
                severity dynamic;
        };
};

zone "." IN {
        type hint;
        file "named.ca";
};
zone "test.cn" IN {
        type master;
        file "test.cn.zone";
};
zone "test1.cn" IN {
        type master;
        file "test1.cn.zone";
};
include "/etc/named.rfc1912.zones";
include "/etc/named.root.key";

[root@tk ~]#

[root@tk ~]# systemctl restart named
// 在B主機上進行測試
[root@gitlab named]# dig @10.0.0.200 www.b.test.cn

; <<>> DiG 9.11.4-P2-RedHat-9.11.4-26.P2.el7_9.8 <<>> @10.0.0.200 www.b.test.cn
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 33847
;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 2
;; WARNING: recursion requested but not available

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;www.b.test.cn.                 IN      A

;; AUTHORITY SECTION:
b.test.cn.              86400   IN      NS      gitlab.test.cn.

;; ADDITIONAL SECTION:
gitlab.test.cn.         86400   IN      A       10.0.0.205

;; Query time: 2 msec
;; SERVER: 10.0.0.200#53(10.0.0.200)
;; WHEN: Thu Dec 23 00:24:37 CST 2021
;; MSG SIZE  rcvd: 79

[root@gitlab named]#