阿里公共DNS 223.5.5.5 和 223.6.6.6是阿里巴巴集团推出的DNS递归解析系统，目标是成为国内互联网基础设施的组成部分，面向互联网用户提供“快速”、“稳定”、“智能”的免费DNS递归解析服务
通过批量测试发现，223.5.5.5 和 223.6.6.6解析不常用域名超慢，达到2-6秒甚至超时解析。这个不知道阿里DNS是什么时候改的，同样对比腾讯119.29.29.29及114DNS 114.114.114.114 及google DNS 8.8.8.8没有这个问题。
批量测试100次，看看返回结果时间:
[root@2 ~]# time for i in `seq 1 100`;do dig @223.6.6.6 www.dnsdizhi.com +short > /dev/null 2>&1; done
real 0m51.319s
user 0m0.215s
sys 0m0.316s
[root@2 ~]# time for i in `seq 1 100`;do dig @223.6.6.6 www.dnsdizhi.com +short > /dev/null 2>&1; done
real 0m3.533s
user 0m0.194s
sys 0m0.346s
[root@2 ~]# time for i in `seq 1 100`;do dig @223.6.6.6 www.dnsdizhi.com +short > /dev/null 2>&1; done
real 0m1.161s
user 0m0.221s
sys 0m0.328s
[root@2 ~]# time for i in `seq 1 100`;do dig @223.6.6.6 www.dnsdizhi.com +short > /dev/null 2>&1; done
real 0m1.135s
user 0m0.210s
sys 0m0.308s
第一个100次，需要51秒，而后面都非常快。
我们详细看看前100次域名解析耗时情况：
第1-10次：
[root@2 ~]# time for i in `seq 1 10`;do time dig @223.6.6.6 www.dnsdizhi.com +short; done
119.28.12.243
real 0m1.134s
user 0m0.004s
sys 0m0.002s
; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.68.rc1.el6_10.1 <<>> @223.6.6.6 www.dnsdizhi.com +short
; (1 server found)
;; global options: +cmd
;; connection timed out; no servers could be reached
real 0m6.005s
user 0m0.002s
sys 0m0.003s
119.28.12.243
real 0m0.032s
user 0m0.003s
sys 0m0.003s
119.28.12.243
real 0m2.072s
user 0m0.003s
sys 0m0.002s
; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.68.rc1.el6_10.1 <<>> @223.6.6.6 www.dnsdizhi.com +short
; (1 server found)
;; global options: +cmd
;; connection timed out; no servers could be reached
real 0m6.005s
user 0m0.001s
sys 0m0.004s
; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.68.rc1.el6_10.1 <<>> @223.6.6.6 www.dnsdizhi.com +short
; (1 server found)
;; global options: +cmd
;; connection timed out; no servers could be reached
real 0m6.006s
user 0m0.003s
sys 0m0.003s
119.28.12.243
real 0m0.009s
user 0m0.001s
sys 0m0.004s
119.28.12.243
real 0m0.037s
user 0m0.002s
sys 0m0.003s
119.28.12.243
real 0m2.032s
user 0m0.002s
sys 0m0.001s
119.28.12.243
real 0m0.012s
user 0m0.002s
sys 0m0.003s
real 0m23.347s
user 0m0.023s
sys 0m0.029s
第11-20次
[root@2 ~]# time for i in `seq 1 10`;do time dig @223.6.6.6 www.dnsdizhi.com +short; done
119.28.12.243
real 0m0.009s
user 0m0.003s
sys 0m0.003s
119.28.12.243
real 0m4.031s
user 0m0.003s
sys 0m0.002s
119.28.12.243
real 0m4.032s
user 0m0.002s
sys 0m0.003s
119.28.12.243
real 0m0.013s
user 0m0.004s
sys 0m0.002s
; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.68.rc1.el6_10.1 <<>> @223.6.6.6 www.dnsdizhi.com +short
; (1 server found)
;; global options: +cmd
;; connection timed out; no servers could be reached
real 0m6.005s
user 0m0.003s
sys 0m0.002s
119.28.12.243
real 0m0.032s
user 0m0.004s
sys 0m0.002s
119.28.12.243
real 0m0.011s
user 0m0.000s
sys 0m0.005s
; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.68.rc1.el6_10.1 <<>> @223.6.6.6 www.dnsdizhi.com +short
; (1 server found)
;; global options: +cmd
;; connection timed out; no servers could be reached
real 0m6.005s
user 0m0.002s
sys 0m0.003s
119.28.12.243
real 0m0.012s
user 0m0.004s
sys 0m0.002s
119.28.12.243
real 0m4.045s
user 0m0.000s
sys 0m0.005s
real 0m24.198s
user 0m0.026s
sys 0m0.029s
第21-30次
[root@2 ~]# time for i in `seq 1 10`;do time dig @223.6.6.6 www.dnsdizhi.com +short; done
; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.68.rc1.el6_10.1 <<>> @223.6.6.6 www.dnsdizhi.com +short
; (1 server found)
;; global options: +cmd
;; connection timed out; no servers could be reached
real 0m6.006s
user 0m0.002s
sys 0m0.003s
119.28.12.243
real 0m0.009s
user 0m0.003s
sys 0m0.003s
119.28.12.243
real 0m0.023s
user 0m0.003s
sys 0m0.002s
119.28.12.243
real 0m0.014s
user 0m0.004s
sys 0m0.001s
119.28.12.243
real 0m0.016s
user 0m0.002s
sys 0m0.002s
119.28.12.243
real 0m4.039s
user 0m0.002s
sys 0m0.003s
; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.68.rc1.el6_10.1 <<>> @223.6.6.6 www.dnsdizhi.com +short
; (1 server found)
;; global options: +cmd
;; connection timed out; no servers could be reached
real 0m6.006s
user 0m0.002s
sys 0m0.004s
119.28.12.243
real 0m0.027s
user 0m0.003s
sys 0m0.002s
; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.68.rc1.el6_10.1 <<>> @223.6.6.6 www.dnsdizhi.com +short
; (1 server found)
;; global options: +cmd
;; connection timed out; no servers could be reached
real 0m6.006s
user 0m0.003s
sys 0m0.003s
119.28.12.243
real 0m0.010s
user 0m0.002s
sys 0m0.003s
real 0m22.156s
user 0m0.027s
sys 0m0.026s
第31-40次
[root@2 ~]# time for i in `seq 1 10`;do time dig @223.6.6.6 www.dnsdizhi.com +short; done
119.28.12.243
real 0m0.012s
user 0m0.001s
sys 0m0.004s
119.28.12.243
real 0m4.076s
user 0m0.003s
sys 0m0.003s
119.28.12.243
real 0m2.026s
user 0m0.003s
sys 0m0.002s
119.28.12.243
real 0m0.025s
user 0m0.005s
sys 0m0.001s
119.28.12.243
real 0m0.033s
user 0m0.002s
sys 0m0.002s
119.28.12.243
real 0m0.026s
user 0m0.002s
sys 0m0.003s
119.28.12.243
real 0m2.026s
user 0m0.003s
sys 0m0.003s
119.28.12.243
real 0m0.026s
user 0m0.002s
sys 0m0.003s
119.28.12.243
real 0m0.010s
user 0m0.001s
sys 0m0.005s
119.28.12.243
real 0m0.028s
user 0m0.002s
sys 0m0.003s
real 0m8.291s
user 0m0.025s
sys 0m0.029s
第41-50次
[root@2 ~]# time for i in `seq 1 10`;do time dig @223.6.6.6 www.dnsdizhi.com +short; done
119.28.12.243
real 0m0.009s
user 0m0.003s
sys 0m0.002s
119.28.12.243
real 0m0.011s
user 0m0.001s
sys 0m0.005s
119.28.12.243
real 0m0.010s
user 0m0.001s
sys 0m0.003s
119.28.12.243
real 0m0.009s
user 0m0.001s
sys 0m0.003s
119.28.12.243
real 0m0.012s
user 0m0.002s
sys 0m0.003s
119.28.12.243
real 0m0.012s
user 0m0.001s
sys 0m0.003s
; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.68.rc1.el6_10.1 <<>> @223.6.6.6 www.dnsdizhi.com +short
; (1 server found)
;; global options: +cmd
;; connection timed out; no servers could be reached
real 0m6.004s
user 0m0.000s
sys 0m0.004s
119.28.12.243
real 0m0.008s
user 0m0.004s
sys 0m0.002s
119.28.12.243
real 0m0.015s
user 0m0.002s
sys 0m0.002s
119.28.12.243
real 0m0.017s
user 0m0.001s
sys 0m0.004s
real 0m6.109s
user 0m0.017s
sys 0m0.032s
第51-60次
[root@2 ~]# time for i in `seq 1 10`;do time dig @223.6.6.6 www.dnsdizhi.com +short; done
119.28.12.243
real 0m0.017s
user 0m0.001s
sys 0m0.005s
119.28.12.243
real 0m0.020s
user 0m0.002s
sys 0m0.003s
119.28.12.243
real 0m0.013s
user 0m0.003s
sys 0m0.002s
119.28.12.243
real 0m0.013s
user 0m0.000s
sys 0m0.006s
119.28.12.243
real 0m0.011s
user 0m0.004s
sys 0m0.001s
119.28.12.243
real 0m0.014s
user 0m0.003s
sys 0m0.002s
; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.68.rc1.el6_10.1 <<>> @223.6.6.6 www.dnsdizhi.com +short
; (1 server found)
;; global options: +cmd
;; connection timed out; no servers could be reached
real 0m6.005s
user 0m0.001s
sys 0m0.004s
119.28.12.243
real 0m0.019s
user 0m0.004s
sys 0m0.001s
119.28.12.243
real 0m0.024s
user 0m0.003s
sys 0m0.003s
119.28.12.243
real 0m0.017s
user 0m0.001s
sys 0m0.003s
real 0m6.155s
user 0m0.022s
sys 0m0.031s
第61-70次
# time for i in `seq 1 10`;do time dig @223.6.6.6 www.dnsdizhi.com +short; done
119.28.12.243
real 0m0.013s
user 0m0.003s
sys 0m0.003s
119.28.12.243
real 0m0.010s
user 0m0.003s
sys 0m0.002s
119.28.12.243
real 0m0.010s
user 0m0.001s
sys 0m0.004s
119.28.12.243
real 0m0.009s
user 0m0.000s
sys 0m0.004s
119.28.12.243
real 0m0.013s
user 0m0.002s
sys 0m0.003s
119.28.12.243
real 0m0.010s
user 0m0.002s
sys 0m0.003s
; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.68.rc1.el6_10.1 <<>> @223.6.6.6 www.dnsdizhi.com +short
; (1 server found)
;; global options: +cmd
;; connection timed out; no servers could be reached
real 0m6.005s
user 0m0.000s
sys 0m0.005s
119.28.12.243
real 0m2.047s
user 0m0.003s
sys 0m0.003s
119.28.12.243
real 0m0.009s
user 0m0.003s
sys 0m0.002s
119.28.12.243
real 0m0.013s
user 0m0.002s
sys 0m0.002s
real 0m8.140s
user 0m0.020s
sys 0m0.031s
第71-80次
# time for i in `seq 1 10`;do time dig @223.6.6.6 www.dnsdizhi.com +short; done
119.28.12.243
real 0m0.010s
user 0m0.002s
sys 0m0.003s
119.28.12.243
real 0m0.012s
user 0m0.001s
sys 0m0.003s
119.28.12.243
real 0m0.013s
user 0m0.002s
sys 0m0.004s
119.28.12.243
real 0m0.009s
user 0m0.001s
sys 0m0.003s
119.28.12.243
real 0m0.014s
user 0m0.001s
sys 0m0.003s
119.28.12.243
real 0m0.045s
user 0m0.004s
sys 0m0.002s
119.28.12.243
real 0m0.012s
user 0m0.001s
sys 0m0.003s
119.28.12.243
real 0m0.013s
user 0m0.001s
sys 0m0.004s
119.28.12.243
real 0m0.010s
user 0m0.000s
sys 0m0.005s
119.28.12.243
real 0m0.011s
user 0m0.002s
sys 0m0.003s
real 0m0.151s
user 0m0.017s
sys 0m0.033s
第81-90次
# time for i in `seq 1 10`;do time dig @223.6.6.6 www.dnsdizhi.com +short; done
119.28.12.243
real 0m0.009s
user 0m0.001s
sys 0m0.004s
119.28.12.243
real 0m0.029s
user 0m0.001s
sys 0m0.005s
119.28.12.243
real 0m0.011s
user 0m0.004s
sys 0m0.001s
119.28.12.243
real 0m0.009s
user 0m0.002s
sys 0m0.002s
119.28.12.243
real 0m0.013s
user 0m0.001s
sys 0m0.006s
119.28.12.243
real 0m0.010s
user 0m0.002s
sys 0m0.003s
119.28.12.243
real 0m0.012s
user 0m0.002s
sys 0m0.003s
119.28.12.243
real 0m0.015s
user 0m0.002s
sys 0m0.003s
119.28.12.243
real 0m0.009s
user 0m0.003s
sys 0m0.002s
119.28.12.243
real 0m0.012s
user 0m0.003s
sys 0m0.002s
real 0m0.131s
user 0m0.023s
sys 0m0.031s
第91-100次
# time for i in `seq 1 10`;do time dig @223.6.6.6 www.dnsdizhi.com +short; done
119.28.12.243
real 0m2.072s
user 0m0.000s
sys 0m0.005s
119.28.12.243
real 0m0.031s
user 0m0.002s
sys 0m0.003s
119.28.12.243
real 0m0.064s
user 0m0.004s
sys 0m0.001s
119.28.12.243
real 0m0.070s
user 0m0.004s
sys 0m0.001s
119.28.12.243
real 0m0.069s
user 0m0.003s
sys 0m0.002s
119.28.12.243
real 0m0.050s
user 0m0.002s
sys 0m0.002s
119.28.12.243
real 0m0.052s
user 0m0.004s
sys 0m0.002s
119.28.12.243
real 0m0.046s
user 0m0.001s
sys 0m0.003s
119.28.12.243
real 0m0.055s
user 0m0.002s
sys 0m0.003s
119.28.12.243
real 0m0.087s
user 0m0.002s
sys 0m0.004s
real 0m2.597s
user 0m0.024s
sys 0m0.027s