DNS原理、架构和配置详解

主域名：my.domain 域名解析服务器172.16.128.80
子域名：blog.my.domain 域名解析服务器 172.16.128.96

主域名的conf文件和zonefile：
zone:
        name: "my.domain"
        zonefile: "/tools/dns/zonefiles/my.domain.zone"

zonefile:
@  IN  SOA  test. hostmaster.my.domain. (
                                        2003080800 ; sn = serial number
                                        172800     ; ref = refresh = 2d
                                        900        ; ret = update retry = 15m
                                        1209600    ; ex = expiry = 2w
                                        30         ; min = minimum = 1h
                                        )
                                        IN    A   100.100.0.176
blog      IN    NS  ns.blog
ns.blog   IN    A   172.16.128.96
www       IN    A   100.100.0.176

子域名服务器的配置：
zone:
        name: "blog.my.domain"
        zonefile: "/tools/dns/zonefiles/blog.my.domain.zone"

zonefile:
@  IN  SOA  test. hostmaster.blog.my.domain. (
                                        2003080800 ; sn = serial number
                                        172800     ; ref = refresh = 2d
                                        900        ; ret = update retry = 15m
                                        1209600    ; ex = expiry = 2w
                                        30         ; min = minimum = 1h
                                        )
                                IN    A   100.100.0.176
www                             IN    A   100.100.0.172

 

; <<>> DiG 9.5.0b2 <<>> @172.16.128.80 www.my.domain
; (1 server found)
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 6301
;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; WARNING: recursion requested but not available

;; QUESTION SECTION:
;www.my.domain.                 IN      A

;; ANSWER SECTION:
www.my.domain.          3600    IN      A       100.100.0.176

;; Query time: 6 msec
;; SERVER: 172.16.128.80#53(172.16.128.80)
;; WHEN: Sun Nov 20 19:19:37 2011
;; MSG SIZE  rcvd: 47

2、在子域名服务器上面查询：www.blog.my.domain，

根据子域名服务器的配置，可以解析出该域名，对应的IP地址为100.100.0.172，下面是查询结果：

; <<>> DiG 9.5.0b2 <<>> @172.16.128.96 www.blog.my.domain
; (1 server found)
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 14554
;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; WARNING: recursion requested but not available

;; QUESTION SECTION:
;www.blog.my.domain.            IN      A

;; ANSWER SECTION:
www.blog.my.domain.     3600    IN      A       100.100.0.172

;; Query time: 5 msec
;; SERVER: 172.16.128.96#53(172.16.128.96)
;; WHEN: Sun Nov 20 19:20:05 2011
;; MSG SIZE  rcvd: 52

从这里也可以看出，最底层的权威域名服务器可以直接作为本地域名解析服务器。

3、到主域名服务器上面查询：www.blog.my.domain地址，由于主域名服务器已经将blog子域授权给字域名服务器，因此预期无法得到具体的网址的IP地址，但是能查询到子域名解析服务器的地址，查询结果符合预期：

; <<>> DiG 9.5.0b2 <<>> @172.16.128.80 www.blog.my.domain
; (1 server found)
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 26575
;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1
;; WARNING: recursion requested but not available

;; QUESTION SECTION:
;www.blog.my.domain.            IN      A

;; AUTHORITY SECTION:
blog.my.domain.         3600    IN      NS      ns.blog.my.domain.

;; ADDITIONAL SECTION:
ns.blog.my.domain.      3600    IN      A       172.16.128.96

;; Query time: 5 msec
;; SERVER: 172.16.128.80#53(172.16.128.80)
;; WHEN: Sun Nov 20 19:20:26 2011
;; MSG SIZE  rcvd: 69

 

再来看一下我们在域名服务提供商那里申请域名的过程，其实申请过程就是将我们需要的域名注册到顶级域名服务器上面去，或者是二级域名服务器上面。如：我们向sina.com.cn申请一个二级域名：abc.sina.com.cn，也就是将这个子域注册到sina域名解析服务器上面去。由于域名服务器需要维护费用，因此域名不是免费的。申请域名一般需要一定的花费。