DNS 递归查询

根域名服务器：13 个域名分布在一千多个服务器上，使用 任播技术 发现最近的根域名服务器

顶级域名服务器（Top Level Domain，TLD）：比如 com、cn、net、org、等

权威域名服务器（Authoritative Domain）：比如 bilibili、qq、baidu、等，管理各自的主机

使用 nslookup 模拟递归查询 www.bilibili.com

set type=ns # name server
set type=a # address

server dns-ip # 和服务器通话

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

> set type=ns				# 查找形式
> .							# 1. 查找根域名服务器
服务器:  UnKnown
Address:  202.204.193.153

非权威应答:
(root)  nameserver = b.root-servers.net
(root)  nameserver = l.root-servers.net
(root)  nameserver = f.root-servers.net
(root)  nameserver = g.root-servers.net
(root)  nameserver = h.root-servers.net
(root)  nameserver = m.root-servers.net
(root)  nameserver = a.root-servers.net
(root)  nameserver = c.root-servers.net
(root)  nameserver = j.root-servers.net
(root)  nameserver = k.root-servers.net
(root)  nameserver = i.root-servers.net
(root)  nameserver = d.root-servers.net
(root)  nameserver = e.root-servers.net
>
> set type=a					# 查看地址
> g.root-servers.net			# 查看这个根域名服务器的地址
服务器:  UnKnown
Address:  202.204.193.153

非权威应答:
名称:    g.root-servers.net
Address:  192.112.36.4

> server 192.112.36.4			# 与根域名服务器通话
默认服务器:  G.ROOT-SERVERS.NET
Address:  192.112.36.4

> set type=ns
>
> com.							# 2. 向根域名服务器咨询 com 域名服务器地址
服务器:  G.ROOT-SERVERS.NET
Address:  192.112.36.4

com     nameserver = a.gtld-servers.net
com     nameserver = d.gtld-servers.net
com     nameserver = f.gtld-servers.net
com     nameserver = h.gtld-servers.net
com     nameserver = g.gtld-servers.net
com     nameserver = j.gtld-servers.net
com     nameserver = c.gtld-servers.net
com     nameserver = b.gtld-servers.net
com     nameserver = l.gtld-servers.net
com     nameserver = k.gtld-servers.net
com     nameserver = e.gtld-servers.net
com     nameserver = m.gtld-servers.net
com     nameserver = i.gtld-servers.net
a.gtld-servers.net      internet address = 192.5.6.30
b.gtld-servers.net      internet address = 192.33.14.30
c.gtld-servers.net      internet address = 192.26.92.30
d.gtld-servers.net      internet address = 192.31.80.30
e.gtld-servers.net      internet address = 192.12.94.30
f.gtld-servers.net      internet address = 192.35.51.30
g.gtld-servers.net      internet address = 192.42.93.30
h.gtld-servers.net      internet address = 192.54.112.30
i.gtld-servers.net      internet address = 192.43.172.30
j.gtld-servers.net      internet address = 192.48.79.30
k.gtld-servers.net      internet address = 192.52.178.30
l.gtld-servers.net      internet address = 192.41.162.30
m.gtld-servers.net      internet address = 192.55.83.30
a.gtld-servers.net      AAAA IPv6 address = 2001:503:a83e::2:30
b.gtld-servers.net      AAAA IPv6 address = 2001:503:231d::2:30
> 
>
> server 192.5.6.30				# 与其中一台顶级域名服务器（gtld，通用顶级域名服务器）建立连接
in-addr.arpa    nameserver = f.in-addr-servers.arpa
in-addr.arpa    nameserver = a.in-addr-servers.arpa
in-addr.arpa    nameserver = c.in-addr-servers.arpa
in-addr.arpa    nameserver = d.in-addr-servers.arpa
in-addr.arpa    nameserver = e.in-addr-servers.arpa
in-addr.arpa    nameserver = b.in-addr-servers.arpa
a.in-addr-servers.arpa  internet address = 199.180.182.53
b.in-addr-servers.arpa  internet address = 199.253.183.183
c.in-addr-servers.arpa  internet address = 196.216.169.10
d.in-addr-servers.arpa  internet address = 200.10.60.53
e.in-addr-servers.arpa  internet address = 203.119.86.101
f.in-addr-servers.arpa  internet address = 193.0.9.1
a.in-addr-servers.arpa  AAAA IPv6 address = 2620:37:e000::53
b.in-addr-servers.arpa  AAAA IPv6 address = 2001:500:87::87
c.in-addr-servers.arpa  AAAA IPv6 address = 2001:43f8:110::10
d.in-addr-servers.arpa  AAAA IPv6 address = 2001:13c7:7010::53
e.in-addr-servers.arpa  AAAA IPv6 address = 2001:dd8:6::101
f.in-addr-servers.arpa  AAAA IPv6 address = 2001:67c:e0::1
默认服务器:  [192.5.6.30]
Address:  192.5.6.30
>
>
> set type=ns
>
> bilibili.com.					# 3. 向顶级域名服务器咨询 bilibili.com 域名服务器的地址
服务器:  [192.5.6.30]
Address:  192.5.6.30

bilibili.com    nameserver = ns3.dnsv5.com
bilibili.com    nameserver = ns4.dnsv5.com
ns3.dnsv5.com   internet address = 129.211.176.212
ns3.dnsv5.com   internet address = 162.14.18.188
ns3.dnsv5.com   internet address = 162.14.24.251
ns3.dnsv5.com   internet address = 162.14.25.251
ns3.dnsv5.com   internet address = 18.194.2.137
ns3.dnsv5.com   internet address = 183.192.201.94
ns3.dnsv5.com   internet address = 223.166.151.16
ns3.dnsv5.com   AAAA IPv6 address = 2402:4e00:1430:1102:0:9136:2b2b:ba61
ns3.dnsv5.com   internet address = 52.77.238.92
ns3.dnsv5.com   internet address = 61.151.180.51
ns4.dnsv5.com   internet address = 101.226.220.12
ns4.dnsv5.com   internet address = 129.211.176.151
ns4.dnsv5.com   internet address = 162.14.24.248
ns4.dnsv5.com   internet address = 162.14.25.248
ns4.dnsv5.com   internet address = 183.192.164.119
ns4.dnsv5.com   internet address = 223.166.151.126
ns4.dnsv5.com   AAAA IPv6 address = 2402:4e00:1020:1264:0:9136:29b6:fc32
ns4.dnsv5.com   internet address = 52.198.159.146
ns4.dnsv5.com   internet address = 59.36.120.147
>
> server 129.211.176.212
(root)  nameserver = f.root-servers.net
(root)  nameserver = g.root-servers.net
(root)  nameserver = h.root-servers.net
(root)  nameserver = i.root-servers.net
(root)  nameserver = j.root-servers.net
(root)  nameserver = k.root-servers.net
(root)  nameserver = l.root-servers.net
(root)  nameserver = m.root-servers.net
(root)  nameserver = a.root-servers.net
(root)  nameserver = b.root-servers.net
(root)  nameserver = c.root-servers.net
(root)  nameserver = d.root-servers.net
(root)  nameserver = e.root-servers.net
默认服务器:  [129.211.176.212]
Address:  129.211.176.212
>
> set type=a
>
> mail.bilibili.com.			# 4. 向权威域名服务器咨询 www.bilibili.com 域名服务器的地址
Server:         129.211.176.212
Address:        129.211.176.212#53

mail.bilibili.com       canonical name = mail.bilibili.com.w.cdngslb.com.
>
> space.bilibili.com.
Server:         129.211.176.212
Address:        129.211.176.212#53

space.bilibili.com      canonical name = a.w.bilicdn1.com.
>
> www.bilibili.com.
Server:         129.211.176.212
Address:        129.211.176.212#53

www.bilibili.com        canonical name = a.w.bilicdn1.com.

参考

• https://www.bilibili.com/video/BV1uL4y1B7aE