Article ID: 111616, created on Jan 5, 2014, last review on May 9, 2014

  • Applies to:
  • Plesk

问题

在邮件日志中有多个错误:

/usr/local/psa/var/log/maillog
---8<---
Jul 11 13:28:31 plesk qmail:1310365711.275186 delivery 1513: deferral:CNAME_lookup_failed_temporarily._(#4.4.3)/
Jul 11 13:29:34 plesk qmail:1310365774.101285 delivery 1514: deferral:CNAME_lookup_failed_temporarily._(#4.4.3)/
Jul 11 13:31:31 plesk qmail:1310365891.566901 delivery 1517: deferral:CNAME_lookup_failed_temporarily._(#4.4.3)/
Jul 11 13:31:36 plesk qmail:1310365896.567026 delivery 1518: deferral:CNAME_lookup_failed_temporarily._(#4.4.3)/
Jul 11 13:31:39 plesk qmail:1310365899.566991 delivery 1519: deferral:CNAME_lookup_failed_temporarily._(#4.4.3)/
Jul 11 13:33:01 plesk qmail:1310365981.655523 delivery 1520: deferral:CNAME_lookup_failed_temporarily._(#4.4.3)/
Jul 11 13:33:11 plesk qmail:1310365991.655422 delivery 1522: deferral:CNAME_lookup_failed_temporarily._(#4.4.3)/
Jul 11 13:33:20 plesk qmail:1310366000.656378 delivery 1521: deferral:CNAME_lookup_failed_temporarily._(#4.4.3)/
Jul 11 13:35:17 plesk qmail:1310366117.655338 delivery 1523: deferral:CNAME_lookup_failed_temporarily._(#4.4.3)/
Jul 11 13:41:41 plesk qmail:1310366501.871498 delivery 1533: deferral:CNAME_lookup_failed_temporarily._(#4.4.3)/
--->8---

原因

无法通过 TCP(如 QMail 尝试操作)查询在 /etc/resolv.conf 中指定的远程 DNS 服务器:

~# host -T -tMX DOMAIN.TLD
;; Connection to NNN.NNN.NNN.NNN1#53(NNN.NNN.NNN.NNN1) for DOMAIN.TLD failed: connection refused.
;; Connection to NNN.NNN.NNN.NNN1#53(NNN.NNN.NNN.NNN1) for DOMAIN.TLD failed: connection refused.
;; connection timed out; no servers could be reached
~#
~# host -tCNAME DOMAIN.TLD
DOMAIN.TLD has no CNAME record
~#


NNN.NNN.NNN.NNNX denotes the remote name servers configured in /etc/resolve.conf:

~# cat /etc/resolv.conf
search plesk.hostname
nameserver NNN.NNN.NNN.NNN1
nameserver NNN.NNN.NNN.NNN2
...

解决方案

要解决此问题,请核实所有 DNS 服务器是否响应 TCP DNS 查询:

# host -tCNAME parallels.com NNN.NNN.NNN.NNN1
;; connection timed out; no servers could be reached
# host -tCNAME parallels.com NNN.NNN.NNN.NNN2
;; connection timed out; no servers could be reached
...


如果失败(如上述实例),请从 /etc/resolve.conf 文件把这些部分注释掉,但是必须要确保至少有一个运行正常的 DNS 服务器。

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