重新发帖，请教高人！

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> [root@redhat-mail root]# nslookup
> set type=mx
> 163.com
Server:         172.23.6.9
Address:        172.23.6.9#53

Non-authoritative answer:
163.com mail exchanger = 10 163mx03.mxmail.netease.com.
163.com mail exchanger = 10 163mx04.mxmail.netease.com.
163.com mail exchanger = 50 163mx00.mxmail.netease.com.
163.com mail exchanger = 10 163mx01.mxmail.netease.com.
163.com mail exchanger = 10 163mx02.mxmail.netease.com.

Authoritative answers can be found from:
.       nameserver = i.root-servers.net.
.       nameserver = j.root-servers.net.
.       nameserver = k.root-servers.net.
.       nameserver = l.root-servers.net.
.       nameserver = m.root-servers.net.
.       nameserver = a.root-servers.net.
.       nameserver = b.root-servers.net.
.       nameserver = c.root-servers.net.
.       nameserver = d.root-servers.net.
.       nameserver = e.root-servers.net.
.       nameserver = f.root-servers.net.
.       nameserver = g.root-servers.net.
.       nameserver = h.root-servers.net.

最郁闷的问题就在这里，能够拿到域名，但是拿不到IP地址。

正常的情况下，应该是这样吧：
Non-authoritative answer:
163.com mail exchanger = 10 163mx01.mxmail.netease.com.
163.com mail exchanger = 10 163mx02.mxmail.netease.com.
163.com mail exchanger = 10 163mx03.mxmail.netease.com.
163.com mail exchanger = 10 163mx04.mxmail.netease.com.
163.com mail exchanger = 50 163mx00.mxmail.netease.com.

Authoritative answers can be found from:
163mx02.mxmail.netease.com      internet address = 220.181.12.81
163mx02.mxmail.netease.com      internet address = 220.181.12.83
163mx02.mxmail.netease.com      internet address = 220.181.12.84
163mx02.mxmail.netease.com      internet address = 220.181.12.85
163mx02.mxmail.netease.com      internet address = 220.181.12.51
163mx02.mxmail.netease.com      internet address = 220.181.12.59
163mx02.mxmail.netease.com      internet address = 220.181.12.60
163mx02.mxmail.netease.com      internet address = 220.181.12.61
163mx02.mxmail.netease.com      internet address = 220.181.12.80
163mx03.mxmail.netease.com      internet address = 220.181.12.75
163mx03.mxmail.netease.com      internet address = 220.181.12.62
163mx03.mxmail.netease.com      internet address = 220.181.12.63
163mx03.mxmail.netease.com      internet address = 220.181.12.64
163mx03.mxmail.netease.com      internet address = 220.181.12.65
163mx03.mxmail.netease.com      internet address = 220.181.12.66
163mx03.mxmail.netease.com      internet address = 220.181.12.67
163mx04.mxmail.netease.com      internet address = 220.181.12.74
163mx04.mxmail.netease.com      internet address = 220.181.12.73
163mx04.mxmail.netease.com      internet address = 220.181.12.76
163mx04.mxmail.netease.com      internet address = 220.181.12.77
163mx04.mxmail.netease.com      internet address = 220.181.12.78
163mx04.mxmail.netease.com      internet address = 220.181.12.68

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哪位DNS高人可以给出解答！