dns 服务器负责匹配域名与 IP，那谁来告诉浏览器（电脑）该域名的 dns 服务器在哪里？

qiuai

2014-03-19 09:59:27 +08:00

你本地网络服务商有个DNS缓存服务器.

lwjef

2014-03-19 10:06:15 +08:00

浏览器不知道。

jasontse

2014-03-19 10:12:04 +08:00

根DNS服务器知道

LazyZhu

2014-03-19 10:32:22 +08:00

浏览器缓存->系统缓存->系统设置DNS缓存->递归DNS缓存->根DNS服务器

Shieffan

2014-03-19 10:38:20 +08:00

DNS Server有Authoritative server跟Recursive Servers。你修改了domain的Name Server，只是修改了此Domain的Authoritative server地址，这个修改会记录在相应的tld server上。

电脑查询是向Recursive Servers发起dns查询，你难道不知道你网络配置里面有dns这个选项？如果是自动获取的话那就有DHCP服务来自动设置dns服务器地址。

jasontse

2014-03-19 10:44:20 +08:00

计算机会向你设置的运营商DNS缓存服务器发出查询请求，缓存服务器就会从根DNS服务器开始一级一级向下查。根DNS服务器的IP是不变的。

查询www.qq.com的完整过程是这样的

; <<>> DiG 9.6.1-P3 <<>> +trace www.qq.com
;; global options: +cmd
. 281408 IN NS h.root-servers.net.
. 281408 IN NS a.root-servers.net.
. 281408 IN NS l.root-servers.net.
. 281408 IN NS g.root-servers.net.
. 281408 IN NS k.root-servers.net.
. 281408 IN NS i.root-servers.net.
. 281408 IN NS c.root-servers.net.
. 281408 IN NS j.root-servers.net.
. 281408 IN NS f.root-servers.net.
. 281408 IN NS d.root-servers.net.
. 281408 IN NS m.root-servers.net.
. 281408 IN NS b.root-servers.net.
. 281408 IN NS e.root-servers.net.
;; Received 228 bytes from 127.0.0.1#53(127.0.0.1) in 59 ms

com. 172800 IN NS e.gtld-servers.net.
com. 172800 IN NS k.gtld-servers.net.
com. 172800 IN NS h.gtld-servers.net.
com. 172800 IN NS j.gtld-servers.net.
com. 172800 IN NS b.gtld-servers.net.
com. 172800 IN NS f.gtld-servers.net.
com. 172800 IN NS d.gtld-servers.net.
com. 172800 IN NS a.gtld-servers.net.
com. 172800 IN NS i.gtld-servers.net.
com. 172800 IN NS l.gtld-servers.net.
com. 172800 IN NS m.gtld-servers.net.
com. 172800 IN NS g.gtld-servers.net.
com. 172800 IN NS c.gtld-servers.net.
;; Received 488 bytes from 202.12.27.33#53(m.root-servers.net) in 112 ms

qq.com. 172800 IN NS ns1.qq.com.
qq.com. 172800 IN NS ns2.qq.com.
qq.com. 172800 IN NS ns3.qq.com.
qq.com. 172800 IN NS ns4.qq.com.
;; Received 244 bytes from 192.43.172.30#53(i.gtld-servers.net) in 347 ms

www.qq.com. 86400 IN NS ns-tel2.qq.com.
www.qq.com. 86400 IN NS ns-tel1.qq.com.
;; Received 136 bytes from 180.153.111.158#53(ns2.qq.com) in 50 ms

www.qq.com. 300 IN A 101.226.129.158
www.qq.com. 300 IN A 101.226.103.106
;; Received 60 bytes from 101.226.66.18#53(ns-tel1.qq.com) in 50 ms