以下是两条到 的跟踪路由82.195.128.132
。一条路由的结果是ns1.hosting365.ie另一个是名字邮件托管365. 为什么有差异?
traceroute to mail.cameracentre.ie (82.195.128.132), 30 hops max, 60 byte packets
1 192.168.1.254 (192.168.1.254) 0.317 ms 0.464 ms 0.608 ms
2 b-ras1.pgs.portlaoise.eircom.net (159.134.155.8) 31.094 ms 34.564 ms 38.634 ms
3 tenge-5-1-1.pe1.pgs.lmk-pgs.eircom.net (86.43.247.133) 39.666 ms 40.829 ms 43.777 ms
4 tenge-7-1-1.core1.bdt.core.eircom.net (86.43.252.249) 48.862 ms 49.052 ms 50.869 ms
5 tenge-1-2-1.pe1.6cr.6cr-6cr.eircom.net (86.43.255.90) 53.900 ms 53.992 ms 56.087 ms
6 83.71.115.181 (83.71.115.181) 58.842 ms 34.027 ms 34.292 ms
7 h365-deg-br1-g3.hosting365.ie (193.242.111.23) 35.718 ms 35.060 ms 35.510 ms
8 0-0-4-dub-dr-001.hosting365.ie (84.51.248.97) 40.193 ms 40.283 ms 44.902 ms
9 0-0-2-dub-ar-004.hosting365.ie (84.51.248.14) 45.136 ms 45.340 ms 49.486 ms
10 bashful.hosting365.ie (82.195.134.70) 49.573 ms 54.386 ms 54.580 ms
11 ns1.hosting365.ie (82.195.128.132) 55.671 ms 56.603 ms 34.909 ms
traceroute to mail.dotser.ie (82.195.128.132), 30 hops max, 60 byte packets
1 192.168.1.254 (192.168.1.254) 0.300 ms 0.374 ms 0.436 ms
2 b-ras1.pgs.portlaoise.eircom.net (159.134.155.8) 31.175 ms 35.508 ms 41.560 ms
3 tenge-5-1-1.pe1.pgs.lmk-pgs.eircom.net (86.43.247.133) 40.325 ms 41.170 ms 43.554 ms
4 tenge-7-1-1.core1.bdt.core.eircom.net (86.43.252.249) 48.668 ms 48.744 ms 50.473 ms
5 tenge-1-2-1.pe1.6cr.6cr-6cr.eircom.net (86.43.255.90) 53.640 ms 53.724 ms 57.679 ms
6 83.71.115.181 (83.71.115.181) 57.994 ms 33.870 ms 36.088 ms
7 h365-deg-br1-g3.hosting365.ie (193.242.111.23) 39.050 ms 34.446 ms 39.256 ms
8 0-0-4-dub-dr-001.hosting365.ie (84.51.248.97) 39.493 ms 43.665 ms 43.883 ms
9 0-0-2-dub-ar-004.hosting365.ie (84.51.248.14) 48.645 ms 48.727 ms 51.290 ms
10 bashful.hosting365.ie (82.195.134.70) 53.648 ms 53.852 ms 56.151 ms
11 mail.hosting365.ie (82.195.128.132) 58.944 ms 59.031 ms 36.878 ms
答案1
82.195.128.132
只是在其“反向 DNS”记录中同时包含这两个名称。
“反向 DNS” 只不过是每个 IP 地址的一个特殊域名;在那里有多个 PTR 记录并不常见,但这是允许的。(甚至允许在那里放置任何其他类型的记录。)
然而,由于 DNS 返回的结果顺序是随机的,而且几乎所有程序都假设一反向 DNS 名称并且只取第一个结果,在反向 DNS 中拥有多个名称可能会导致与此问题完全相同的混淆 - 即名称似乎是随机选择的。
$ dig +noall +answer 132.128.195.82.in-addr.arpa.ptr 132.128.195.82.in-addr.arpa.3527 IN PTR mail.hosting365.ie。 132.128.195.82.in-addr.arpa.3527 IN PTR ns1.hosting365.ie。
$主机82.195.128.132 132.128.195.82.in-addr.arpa 域名指针 mail.hosting365.ie。 132.128.195.82.in-addr.arpa 域名指针 ns1.hosting365.ie。
答案2
PTR
该 IP 地址有两条记录:
$ dig -x 82.195.128.132
...
;; ANSWER SECTION:
132.128.195.82.in-addr.arpa. 3584 IN PTR mail.hosting365.ie.
132.128.195.82.in-addr.arpa. 3584 IN PTR ns1.hosting365.ie.
有趣的是,自从我开始写作以来,这种情况发生了变化!我现在只看到
132.128.195.82.in-addr.arpa. 3479 IN PTR mail.hosting365.ie.