从根名称服务器开始使用nslookup解析DNS的过程

Question

我大致理解DNS解析器如何通过域层次结构查询名称服务器，向下解析根名称空间中的域名，但是我想尝试使用nslookup查找google.com名称服务器(或任何其他域名作为示例)来执行类似的过程。我知道我能做的就是：

nslookup -type=ns google.com

它将返回google.com的所有名称服务器，如ns1.google.com、ns2.google.com等。

然而，我想要做的是从根级域递归地进入Google的名称服务器，类似于DNS解析器通常会做的事情(假设没有缓存命中)。

下面是我尝试过的过程：

1. 首先获取根级名称服务器: nslookup -type=ns。这将返回所有13个根服务器，我选择了其中一个: 192.36.148.17
2. 现在，我按照如下方式查询gTLD .com的根名称服务器: nslookup -type=ns com 192.36.148.17它返回一个名称服务器列表，即IP: 199.212.0.73
3. 我现在使用第一个名称服务器的IP来查询SLD的名称服务器: nslookup -type=ns google.com 199.212.0.73

在这里，我本以为这会返回google.com的名称服务器，但我得到的是名称服务器，如v.arin.net、u.arin.net等。我在这里缺少什么？

Answer 1

这似乎是因为您在步骤3中使用的是来自arpa的IP而不是gtld服务器，下面是我所做的，并且工作得很好，使用arpa中的任何ip都会返回与您遇到的相同的结果。

1) nslookup -type=ns .

nslookup -type=ns .
Server:  google-public-dns-a.google.com
Address:  8.8.8.8

Non-authoritative answer:
(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
(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

2)解决IP

问题

Pinging i.root-servers.net [192.36.148.17] with 32 bytes of data:
Reply from 192.36.148.17: bytes=32 time=30ms TTL=53
Reply from 192.36.148.17: bytes=32 time=27ms TTL=53
Reply from 192.36.148.17: bytes=32 time=27ms TTL=53
Reply from 192.36.148.17: bytes=32 time=30ms TTL=53

Ping statistics for 192.36.148.17:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 27ms, Maximum = 30ms, Average = 28ms

3)查询-type=ns com 192.36.148.17

nslookup -type=ns com 192.36.148.17
in-addr.arpa    nameserver = e.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 = b.in-addr-servers.arpa
in-addr.arpa    nameserver = f.in-addr-servers.arpa
in-addr.arpa    nameserver = a.in-addr-servers.arpa
a.in-addr-servers.arpa  internet address = 199.212.0.73
a.in-addr-servers.arpa  AAAA IPv6 address = 2001:500:13::73
b.in-addr-servers.arpa  internet address = 199.253.183.183
b.in-addr-servers.arpa  AAAA IPv6 address = 2001:500:87::87
c.in-addr-servers.arpa  internet address = 196.216.169.10
c.in-addr-servers.arpa  AAAA IPv6 address = 2001:43f8:110::10
d.in-addr-servers.arpa  internet address = 200.10.60.53
d.in-addr-servers.arpa  AAAA IPv6 address = 2001:13c7:7010::53
e.in-addr-servers.arpa  internet address = 203.119.86.101
e.in-addr-servers.arpa  AAAA IPv6 address = 2001:dd8:6::101
f.in-addr-servers.arpa  internet address = 193.0.9.1
f.in-addr-servers.arpa  AAAA IPv6 address = 2001:67c:e0::1
Server:  UnKnown
Address:  192.36.148.17

com     nameserver = j.gtld-servers.net
com     nameserver = i.gtld-servers.net
com     nameserver = g.gtld-servers.net
com     nameserver = e.gtld-servers.net
com     nameserver = h.gtld-servers.net
com     nameserver = m.gtld-servers.net
com     nameserver = b.gtld-servers.net
com     nameserver = d.gtld-servers.net
com     nameserver = k.gtld-servers.net
com     nameserver = a.gtld-servers.net
com     nameserver = l.gtld-servers.net
com     nameserver = f.gtld-servers.net
com     nameserver = c.gtld-servers.net
a.gtld-servers.net      internet address = 192.5.6.30
a.gtld-servers.net      AAAA IPv6 address = 2001:503:a83e::2:30
b.gtld-servers.net      internet address = 192.33.14.30
b.gtld-servers.net      AAAA IPv6 address = 2001:503:231d::2:30
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

4)查找-type=ns google.com 192.5.6.30

nslookup -type=ns google.com 192.5.6.30
(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
(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
Server:  UnKnown
Address:  192.5.6.30

google.com      nameserver = ns2.google.com
google.com      nameserver = ns1.google.com
google.com      nameserver = ns3.google.com
google.com      nameserver = ns4.google.com
ns2.google.com  internet address = 216.239.34.10
ns1.google.com  internet address = 216.239.32.10
ns3.google.com  internet address = 216.239.36.10
ns4.google.com  internet address = 216.239.38.10